1B and D), implying that as priming with DbPA224 normally stimulates a much broader spectrum of TCRβ than is the case for DbNP366, this diversity could help to ensure the integrity of the response when TCRα is limiting. Interestingly, the DbNP366>DbPA224 BAY 80-6946 order immunodominance hierarchy recognized for secondary responses to wt influenza A viruses in H2b mice 21 was no longer maintained in A7 transgenics (Fig. 1E–H). Similar to

the primary response (Fig. 1A–D), the DbNPCD8+ sets recovered from the spleen (Fig. 1E and G) and BAL (Fig. 1F and H) of the secondarily infected A7 mice were reduced in magnitude (p<0.05) compared with those from the B6 controls. A possible explanation is that some of the DbNP366-specific TCRβ that pair with this irrelevant Vα chain may not form TCR that can be efficiently recruited after secondary challenge, leading to the A7 DbNPCD8+ and DbPACD8+ recall responses being of comparable magnitude. The next question was whether limiting the available TCRαβ pairs by confining the response to an “irrelevant” TCRα in any way reflects that such “aberrantly selected” TCRαβ use a different

mode of pMHC-I recognition. We made sequential alanine (A) substitutions at different positions within NP366–374 and PA224–233 peptides, excluding the anchor residues (p5, p9 for NP366; p5, p10 for selleck PA224). These mutant NP366 and PA224 peptides were used to probe CD8+ T-cell responsiveness as determined by IFN-γ production. The recognition profiles of polyclonal DbNPCD8+ and DbPACD8+ T cells obtained from mice primed-and-boosted with influenza viruses (H1N1 then H3N2) were modified by different aa substitutions (Fig. 2A and B). Following infection of A7 mice, p6M and p4E were critical for TCR recognition by DbNPCD8+ T cells (Fig. 2A), whereas p6F and p7R were important for DbPACD8+ T cells (Fig. 2B). These Carnitine palmitoyltransferase II profiles were identical to those found previously for B6 mice (Fig. 2) 17, 22. It thus seems that the Vα2-constrained and DbNP366- and DbPA224-specific TCR recognize the same features within the antigenic peptides, raising the question of whether the DbNP366 and DbPA224 epitopes are recognized by the same CDR3β clonotypes in A7 and wt B6

animals. Furthermore, these peptide recognition data suggest that the Vβ-chain may play a dominant role in antigen recognition for both DbNPCD8+ and DbPACD8+ T-cell responses. Alternatively, for the Vα chain to participate in pMHC-I recognition, it might be expected not to have any structural features that would interfere with pMHC-I docking in A7 mice. To determine the clonal composition defined by TCRβ diversity, the DbNP366-specific CD8+ T cells were first analyzed for Vβ usage by staining with a panel of anti-Vβ mAb. In B6 mice, Vβ8.3 consistently accounts for an average of 42.8% 14, 23 of the DbNPCD8+ response, with Vβ4 24 being subdominant (∼13%). This strong Vβ8.3 bias was no longer apparent for the A7 mice (Fig. 3A). However, Vβ4 emerged for DbNP366-specific T cells from spleen (51.4%; range 18.

If a significant time effect was found we described this as a diurnal rhythm. The nTreg-mediated suppression of cytokine synthesis was analyzed using a paired t-test comparing cytokine concentrations in culture supernatants with versus without nTreg. To assess temporal relationships between serum/plasma levels of hormones and cytokine secretion by CD4+ CD25− T cells and their suppression by nTreg, a backward multiple linear regression analysis was calculated. For these analyses individual data were normalized by Z-transformation. Before we analyzed the diurnal Tres and

nTreg activities we compared whether T cells, isolated and sorted using MACS, would give the same results. We observed that MACS-isolated nTreg (Fig. 1), as well as MACS-sorted

nTreg (Fig. S1), significantly suppressed IL-2, IFN-γ and TNF-α secretion by polyclonally stimulated CD4+ CD25− Tres. By MG-132 concentration contrast, the secretion of IL-4, IL-6, IL-10 and IL-17 was not suppressed. For IL-10 and IL-17A, we detected an increase in supernatant levels only if sorted nTreg were added (Figs 1  and S1). Because the assays with MACS-isolated and MACS-sorted T cells produced strikingly similar results, we chose the MACS isolation protocol (which for logistical reasons was more appropriate for the diurnal approach) for diurnal Tres and nTreg activity analyses. NVP-AUY922 molecular weight We also investigated whether αCD3-activated nTreg secrete cytokines and discovered substantial amounts of IL-6, IL-10 and IL-17A, but almost no IL-2, IL-4,

IFN-γ or TNF-α, in the culture supernatants (Figs 1 and S1). Negative controls included adherent cells that were stimulated with αCD3-mAb. None of the analyzed cytokines were detected in these Methane monooxygenase controls (data not shown). These data show that nTreg are suppressors of IL-2, IFN-γ and TNF-α secretion, but not of IL-4, IL-6, IL-10, or IL-17A secretion. Furthermore, our results suggest that nTreg are selective producers of IL-6, IL-10 and IL-17A. To rule out the possibility that cultured nTreg were contaminated with other T cells we cultured CFSE-stained nTreg in co-culture with unstained Tres and measured nTreg proliferation after 62 hr of stimulation with αCD3-mAb in the presence of adherent cells. We did not, however, observe any proliferation of nTreg (Fig. S2). To confirm the nTreg-mediated suppression of cytokine secretion by Tres (shown above), we investigated the reduced proliferation of cytokine-producing Tres through the addition of nTreg, at a single-cell level, using flow cytometry. After culturing Tres in the presence or absence of nTreg, we restimulated the cultures and then co-stained them with αCD4-mAb and αIL-2-, αIL-4-, αIL-10-, αIL-17A, αIFN-γ-, or αTNF-α-mAb. We then quantified the percentage of proliferating, cytokine-producing Tres (Fig. 2a).

A role for SEMA3A in termination of DC/T-cell interactions by repulsive destabilization of the conjugates on NP-1 interaction has been proposed 34, and in line with this, SEMA3A was produced only late after onset of allogeneic MLRs (34 and Fig. 4B). In contrast, SEMA3A production from MV-DC alone or in co-cultures with allogeneic T cells raised within few hours, indicating that this might contribute to destabilization of the IS as described to occur in these cultures earlier 10 and as evidenced by lower frequencies of stable conjugates on exogenous addition of SEMA3A (and also SEMA6A)(Fig.

6B). Notably, amounts of SEMA3A released from MV-DC/T-cell co-cultures several fold exceeded those determined to actively inhibit T-cell selleck compound expansion stimulated allogeneic CHIR-99021 purchase LPS-DC 34 or on αCD3/CD28 ligation 36. In line with previous reports 38, 39, we repeatedly detected especially in the co-cultures, at least two SEMA3A species (Fig. 4B), the generation of may involve intracellular or surface proteolytic processing, e.g. furin or membrane-resident metalloproteases 48. Whether production of two species in the MV-DC/T-cell cocultures relates to higher infection levels (as compared to the MV-DC only, Fig. 4A) or to the presence of allogeneic T cells remains to be resolved.

While abrogation of NP-1/SEMA3A interaction reportedly signficantly improved allogeneic T-cell expansion driven by LPS-DC 34, this and conjugate stability in MV-DC/T-cell co-cultures could not detectably be rescued by SEMA-neutralizing

antibodies (not shown). This is, however, not surprising since the presence of the MV gp complex on the DC surface within the DC/T-cell interface has previously been linked to IS destabilization and contact-mediated inhibition of T-cell expansion 10, 47, 49, 50. It is also because MV particles selleck screening library displaying the inhibitory complex were likely present in conditioned supernatants of MV-DC or MV-DC/T-cell co-cultures containing high levels of SEMA3A that we did not directly prove their activity on αCD3/CD28-stimulated T-cell expansion. In contrast to earlier studies 34, 36, SEMA6A was at least as efficient at interferring with IS stability and function as SEMA3A (Fig. 6B). As the IgG control always included at comparable levels did not have any effect on all parameters determined except for T-cell motility (Fig. 6A), and ligation of murine plexA4 by SEMA6A is known to negatively regulate T-cell responses 51, we consider the activity of SEMA6A in the assay as specific and thus, the obvious discrepancy cannot be explained at present, and needs further experimentation which would, as the identification of the cellular source of SEMA6A, exceed the present study.

Caspofungin and POS were purchased as the products for clinical use (Cancidas®; Merck & Co., Inc., 50 mg powder for intravenous infusion; Noxafil®; Schering-Plough Co., 40 mg ml−1 oral suspension) In the prescription for oral suspension form of POS ‘Noxafil’, there are no excipients with any antimicrobial

activity. The powder of Cancidas® Daporinad research buy was diluted in distilled water and used as a fresh suspension. For the final concentrations, the antifungal agents were diluted in RPMI 1640 medium with L-glutamine and without sodium bicarbonate (Sigma, Chemical Co, St Louis, MO, USA), buffered with 3-[N-morpholino]propanensulfonic acid (MOPS) (Sigma, Chemical Co).12 The final concentrations of tested antifungal agents used to determine

the minimal inhibitory concentration (MIC) on planktonic cells were 0.007–16 μg ml−1. The concentration of antifungals used to examine the minimal inhibitory concentration on biofilm was in accordance with respective MIC for planktonic cells (1 × , 2 × , 4 × , 8 × , 16 × , 32 × , 64 × , 128 × MIC). The minimal inhibitory concentrations (MICs) were performed using the microdilution method in accordance with the guidelines of the Clinical and Laboratory Standards Institute (CLSI) document M27/A2.13 The yeast inoculum was adjusted to a concentration of 0.5 × 103–2.5 × 103 CFU/ml in MOPS buffered RPMI 1640 medium. The microtitre plates were incubated at 35 °C for 48 h. The lowest concentration inhibiting any visible growth was used as the MIC for AMB and CAS, whereas the lowest concentration associated with a significant reduction Bumetanide in turbidity compared with the control well was used as the MIC for selleck kinase inhibitor POS.13 Owing to the lack of interpretive breakpoints for amphotericin B, CAS and POS according to CLSI, a categorical assignment was not possible. However, we used recent published data to select breakpoints for resistance as follows: ≥1 for amphotericin B14 and ≥2 for CAS.15 Antifungal activities against C. albicans biofilms were studied using the standardised static microtitre plate model measured by 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[8phenylamino)

carbonyl]-2H-tetrazolium hydroxide (XTT) (Sigma, Chemical Co) reduction assay established by Ramage et al.12 Briefly, freshly grown C. albicans colonies taken from a Sabouraud agar plate were inoculated in yeast peptone glucose medium (1% [wt/vol] yeast extract, 2% [wt/vol] peptone 2% [wt/vol] glucose) (YPG) (Oxoid LTD, Basingstoke, Hampshire, England). Flasks containing 20 ml yeast suspension in YPG medium were incubated over night in an orbital shaker (100 rpm) at 35 °C. Cells were washed twice in sterile phosphate buffered saline (PBS, 10 mmol l−1 phosphate buffer, 2.7 mmol l−1 potassium chloride, 137 mmol l−1 sodium chloride [pH 7.4]) (Morphisto, Frankfurkt am Main, Germany) and resuspended in RPMI 1640 to a cellular density equivalent to 1 × 106 CFU/ml.

With the next set of experiments we addressed the question whether surface IgE-positive B cells can be detected in IgE knock-in mice. First, we stimulated total spleen cells for 5 days with LPS and IL-4. We used IgE knock-in mice on the CD23−/− background in order to avoid passive binding of soluble Small molecule library cell line IgE to the low

affinity IgE receptor (CD23) on B cells [23]. Surface IgE and IgG1 were detected by flow cytometry. LPS alone neither induced significant IgE nor IgG1 expression (0.4–1.5%) (Fig. 2A and Supporting Information Fig. 1). In B cells from WT mice LPS+IL-4 induces IgG1 (23%), but only very little IgE (1.5%). In contrast, both cells isolated from either heterozygous or homozygous IgE knock-in mice express comparably high amounts of IgE (ca. 15%) on the cell surface. However, the learn more small fraction of positively stained cells might be due to a cross-reactivity or background staining of

the detection antibodies (see also Fig. 2E). WT mice express 23% and heterozygous IgE knock-in mice 10% IgG1 and, as predicted, no IgG1 was found in IgEki/ki mice. These results suggest that in vitro the chimeric membrane IgE molecule can be transported to the surface with a slightly lower efficiency than natural IgG1. To confirm these results, we performed a RT-PCR analysis of the membrane forms of IgE, IgG1, and the chimeric membrane IgG1-IgE form (Fig. 2B). The results of LPS+IL-4 stimulated cultures are in line with the protein expression data (Fig. 2A); however, LPS alone induces mRNA transcripts with little IgG1 or chimeric IgE being expressed on the surface of the cells (Fig. 2B). Second, we analyzed B cells from bone marrow, lymph nodes (data not shown), and spleens of heterozygous IgE knock-in mice and their WT littermates. We could find a normal B-cell subset distribution in vivo (data not shown). However, we could not detect membrane IgE-positive B cells (Fig. 2C) in the

spleen. The absence of CD23 demonstrates that the increase in IgE expression is not a result of an increase in membrane IgE expressing B cells in unchallenged, naïve mice (Fig. 2C) [23]. Additionally, immunization and boost with the T-dependent antigen oxyclozanide trinitro-phenyl-chicken ovalbumin (TNP-OVA) and the subsequent immunohistochemical analysis of splenic B-cell follicles shows only very rare IgE-positive cells located at the edge of the B-cell follicle in IgE knock-in mice of the CD23−/− background (Fig. 2D). Surface IgE and IgG1 expression in vivo were then analyzed after infection with the helminth Nippostrongyus brasiliensis (Nb), which leads to pronounced Th-2 responses [29]. Mesenteric lymph nodes of IgEki/ki, IgEki/wt, and WT mice were taken at day 14 after infection, at the peak of the germinal center response. IgEki/ki mice, as expected, showed no staining for IgG1, whereas IgEki/wt had intermediate expression of surface IgG1 when compared to WT.

Rats homozygous for IgM mutation generate truncated Cμ mRNA with a de novo stop codon and no Cγ mRNA. JH-deletion rats showed undetectable mRNA for all H-chain transcripts. No serum IgM, IgG, IgA and IgE were detected in these rat lines. In both lines, lymphoid B-cell numbers were reduced

>95% versus WT animals. In rats homozygous for IgM mutation, no Ab-mediated hyperacute allograft rejection was encountered. Similarities in B-cell differentiation seen in Ig KO rats and ES cell-derived Ig KO mice are discussed. These Ig and B-cell-deficient rats obtained using zinc-finger nucleases-technology should be useful as biomedical research models and a powerful platform for transgenic Selumetinib animals expressing a human Ab repertoire. The derivation of genetically engineered animals addresses basic biological problems, generates disease models and helps to develop new biotechnology tools 1, 2. Although ES-cell-derived mice carrying introduced gene mutations

have provided invaluable information, the availability of other species with engineered gene alterations is limited. For over 100 years, the rat has been an experimental species of choice in many biomedical research areas CHIR-99021 and in biotechnological applications 3, 4. During the last 15 years, genetic engineering techniques have resulted in the generation of many transgenic and non-targeted mutated rats 1, 3, 4. This has confirmed and complemented disease studies but, as well as presenting biotechnological Dimethyl sulfoxide alternatives, also generated new paradigms. Nevertheless, the development of gene-targeted mutated rats was hampered by the absence of rat ES cells or robust cloning techniques. In 2008, rat ES cells were described 5, 6 but as yet there have been no reports on the generation of mutant rats from such cells. In 2009, we reported

for the first time the generation of IgM-specific alterations directly in rats using zinc-finger nucleases (ZFN) 7–9. ZFN are new versatile and efficient tools that have been used to generate several genetically modified organisms such as plants, Drosophila, zebra fish and rats as well as human ES cells 7. ZFN are hybrid molecules composed of a designed polymeric zinc finger domain specific for a DNA target sequence and a FokI nuclease cleavage domain 10. Since FokI requires dimerization to cut DNA, the binding of two heterodimers of designed ZFN-FokI hybrid molecules to two contiguous target sequences in each DNA strand separated by a 5–6 bp cleavage site results in FokI dimerization and subsequent DNA cleavage 10.

During these analyses, SCH727965 price it was noticed that there were two forms of cellular mass displaying different histological characteristics (Fig. 2). In one type, cells were confined to a single layer of the skin, surrounded by normal tissue (Fig. 2a,b); however, in the other type,

inflammatory cells were found spread throughout the layers of the skin (Fig. 2c,d). Upon assessment of sections for these characteristics, none of the sections from PC61-treated mice, and around half of the GL113-treated mice, displayed the ‘confined’ phenotype (Fig. 2e). This is noteworthy when compared with the percentage of mice that reject these tumours; approximately 50% in GL113-treated mice and 100% in PC61-treated mice.9 To perform a more quantitative assessment of the differences between cellular masses termed ‘confined’ versus those termed ‘non-confined’, the total volume of each cellular mass within the GL113-treated and PC61-treated groups (> 4 per group),

4 and 24 hr Ku-0059436 research buy after tumour cell inoculation, was calculated. These data, shown in Fig. 3(a), corroborated our previous observation in that at 24 hr larger masses were observed in the PC61 group compared with those treated with GL113. At later time-points (96 hr), larger cellular masses were measured in the latter, control group of mice, coinciding with detection of live tumour cells in this group. Live tumour cells were identified by histological examination of H&E-stained Vorinostat order sections in GL113-treated mice but not in PC61-treated mice. In the former group, within the tumour cell mass, amid cell debris, there are areas of homogeneous healthy cells, forming foci of organized tissue, similar to that seen in large, established tumours (Fig. 3b,c). These data are consistent with the observation that around 50% of mice inoculated with B16FasL develop palpable tumours whereas tumours

are rarely seen in B16FasL-inoculated mice pre-treated with PC61.9 Overall, these data indicate that an inflammatory infiltrate into the tumour creates a disorganized, non-confined mass that is associated with tumour cell death and tumour rejection, favoured by depletion of Treg cells by PC61 mAbs. We were struck by how rapidly Treg-cell depletion affected the accumulation of inflammatory cells at the site of the tumour cell inoculum. The ability of Treg cells to suppress an inflammatory response within hours of an antigenic challenge and at a peripheral site implies that skin-resident Treg cells are rapidly mobilized. To visualize Treg cells at the site of tumour cell challenge, skin sections were stained with Foxp3-specific mAbs. Foxp3+ cells were found in the skin and particularly at the site of tumour cell inoculation (Fig. 4). This is in agreement with other studies reporting Treg-cell identification in the skin of mice16 and humans.17 Stained cells were not observed in sections prepared from PC61-treated mice (data not shown).

As shown in Fig. 1, αDC1s produced significantly higher amounts of the CXCR3 ligands CXCL9/MIG (P = 0.02), CXCL10/IP-10 (P = 0.02) and CXCL11/I-TAC (P = 0.03) (Fig. 1a–c), as compared with PGE2DCs. This chemokine production was not seemingly depressed by the number of contaminating CLL cells Forskolin in vitro in the cultures (Fig. 1D). Both

PGE2DCs, as well as αDC1s, showed a mature DC phenotype and morphology (Fig. 2). Importantly, loading with heat-stressed necrotic CLL cells had no significant impact on chemokine production or phenotype. Previously, it has been shown that PGE2DCs generated from healthy blood donors preferentially produced CCL22/MDC and attracted Tregs [17]. In line with this, we could show that monocyte-derived PGE2DCs from patients with CLL produced significantly higher levels of the Th2- and Treg-attracting chemokine CCL22/MDC as compared with αDC1 (P = 0.03). Regarding the production of CCL17/TARC, no statistical significant difference was found (Fig. 3A,B). Once again, tumour cell loading had no significant impact on chemokine production. To examine whether the high production of CXCR3-ligands by αDC1s could be translated into possible recruitment of NK and NKT cells, we used a transwell plate migration assay. Even though there were no differences in total number of recruited lymphocytes, we found that supernatants from tumour-loaded αDC1s induced a substantially higher recruitment of NK (P = 0.04) and NKT (P = 0.04) cells from PBMC in transwell

Kinase Inhibitor Library research buy experiments compared with supernatants from tumour-loaded PGE2DCs (Fig. 4A,B). When reaching the lymph node, antigen-loaded mature DCs undergo an additional activation step, termed ‘licensing’ in response to various stimuli, notably CD40 ligand that is expressed on cognate CD4+ T cells. Signalling through CD40 has multiple effects on DCs, inducing the upregulation of costimulatory molecules and the secretion of cytokines either and chemokines. Effective vaccine DCs should optimally mediate a CD4+ T cell-dependent guiding of rare tumour-specific CD8+ T cells to site of antigen-dependent DC–CD4+

T cell interactions by secretion of CCL3/MIP-1α and CCL4/MIP-1β chemokines [20]. We therefore considered whether differentially matured DCs were able to respond to subsequent CD40 ligation (mimicking CD4+ T cell interaction). To optimally mimic the situation in vivo, previously washed mature DCs were cultured in fresh medium for further 24 h (this being an estimation of the time required for the DCs to migrate to a draining lymph node) and subsequently washed before CD40 stimulation by cross-linked soluble CD40L. We found that tumour-loaded αDC1s, produced larger amounts of CCL3 (P = 0.02) and CCL4 (P = 0.04) after CD40 ligation, as compared with PGE2DCs (Fig. 5A,B). Finally, we could show, in accordance with Lee et al. [24], that tumour-loaded αDC1s were superior in producing the Th1-deviating IL-12p70 cytokine compared with PGE2DCs (P = 0.02) after CD40 ligation (Fig. 5C).

g. impaired viral clearance. Genetically modified DCs have also been employed in preclinical models of type 1 diabetes. BMDCs transduced with a lentiviral vector encoding IL-4 were able to prevent disease in old (12-week-old)

NOD recipients, i.e. well after the onset of insulitis, whereas unmodified DCs could not [60]. BMDCs engineered to express galectin-1 by transduction with a recombinant adenovirus were capable of delaying the onset of diabetes induced in immunodeficient NOD recipients by transfer of splenocytes from diabetic NOD females [61]. This is consistent with the recent finding that stimuli that induce tolerogenic DCs, such as IL-10 and 1,25-dihydroxyvitamin D3, also Syk inhibitor increase their expression of galectin-1 [62]. In addition to viral vectors, treatment with anti-sense oligonucleotides has been used to engineer DCs having a tolerogenic phenotype. Giannoukakis and Trucco used anti-sense oligonucleotides targeting the CD40, CD80 and CD86 messages to treat BMDCs from NOD mice in order to GSK 3 inhibitor engineer phenotypically immature DCs [63]. When

these DCs were administered intraperitoneally to 5–8-week-old NOD mice, a single injection was able to prolong the time to diabetes onset. The therapeutic effect correlated with an increased percentage of splenic CD4+CD25+ (presumably regulatory) T cells. Systemic immunosuppression was not observed, as splenocytes from DC-treated mice were able to respond to alloantigens in vitro. These investigators showed subsequently that four weekly injections of anti-sense oligonucleotide-treated DCs, beginning at 8 weeks of age, resulted in prevention of disease in all recipients [50]. BMDCs from NOD mice have also been manipulated by treatment with decoy double-stranded oligonucleotides containing nuclear factor-kappa

B (NF-κB) binding sites [64]. The treated DCs exhibited reduced NF-κB activity and suppression of co-stimulatory molecule expression and IL-12 production. When administered as a single intravenous injection to NOD mice at 6–7 weeks of age, NF-κB-deficient DCs had a dramatic disease-preventive effect, while untreated DCs or those treated with control oligonucleotides were only modestly beneficial. When Ureohydrolase contemplating therapeutic administration of DCs, it is important to consider the in vivo trafficking patterns of the administered cells. Creusot and Fathman showed that BMDCs administered intraperitoneally to mice accumulated preferentially in the pancreatic lymph nodes as opposed to other lymph nodes or the spleen [65]. This was the case even in non-diabetes-prone mouse strains. This could explain why intraperitoneal administration of anti-sense oligonucleotide-treated DCs delayed diabetes onset but did not result in systemic immunosuppression [63].

Acute exposure of control lambs to L3 larvae of H. contortus on day 11 (Figure 1) may have elicited a vaccination response in control lambs

(31,32) and may explain breed differences in total circulating IgE at days 14, 17, 19 and 27; lymph RG7204 mouse node total IgE at days 17 and 27 and eosinophil counts at day 17. None of these breed differences remained significant in control lambs after day 27. Contrasts between immune responses in hair and wool lambs thus specifically represent effects of infection at day 0 following de-worming at day −11, −8, and −3 in infected lambs and effects of de-worming at days −11, −8 and 8, acute exposure to L3 antigen at day 11, and subsequent additional de-wormings at days 12 and 14 in control lambs. Lambs of both groups had experienced prior exposure to H. contortus, including a controlled chronic infection for 3 weeks before the start of the study. Comparisons of treated and control lambs thus contrast responses to two different immunostimulatory regimens. Wool sheep had lower PCV at day 21 p.i. and nearly threefold selleck inhibitor higher FEC compared with hair sheep, but these breed differences in this small sample of sheep only approached significance. However, previous studies with larger numbers of animals confirm that Caribbean hair sheep are more resistant to experimental and natural H. contortus, as assessed

by FEC, PCV and worm burden than conventional wool breeds such as the Dorset, Suffolk, Hampshire and Dorset × Rambouillet crosses (3,4,18,33). Similar breed differences in FEC exist between

6-month-old Barbados Blackbelly (another resistant Caribbean hair breed) Amoxicillin and INRA 401 (a wool composite) sheep (34). We also found a moderate correlation between FEC and PCV in agreement with other studies (35,36). St. Croix hair sheep had fewer adult worms in their abomasa compared with the wool composite. Gamble and Zajac (18) likewise reported that St. Croix hair lambs undergoing sustained natural infection had fewer worms than co-grazing Dorset lambs and similar results have been reported in other resistant hair breeds (34,43). Our correlation of 0·71 between FEC and worm burden was positive, significant and almost identical to that reported in Florida Native sheep (16). Even higher correlations (0·85–0·91) have been reported in wool sheep divergently selected on FEC (15). The lower worm burdens in hair sheep in these studies may result from either poor establishment or expulsion of adult worms. Abomasal lymph nodes are the centre for immune cell chemotaxis, antigen recognition and cell proliferation during abomasal infection. In this study, abomasal lymph nodes increased significantly in weight because of infection, with heavier lymph nodes in infected hair compared with wool sheep despite their smaller mean body weight. Balic et al. (21) reported a twofold increase in abomasal lymph node weight because of H.