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PubMed1995

An enzyme immunoassay for rat soluble MHC class I molecules (RT1a) and the release of soluble class I from mitogenically stimulated mononuclear cells.

Soluble MHC class I antigens can be detected in the serum of humans and various animals and appear in the circulation shortly after liver transplantation. The precise role of these antigens is currently uncertain, but soluble MHC class I may be involved in immunomodulation. We have developed an enzyme linked immunosorbent assay for soluble rat MHC class I (RT1a) molecules and monitored the kinetics of antigen release following in vitro stimulation of splenic mononuclear cells. A 4 day DA splenocyte Con A supernatant provided a source of soluble class I antigens and was arbitrarily assigned a concentration of 1000 units/ml. Ninety six well plates were coated with a rat RT1a-specific mAb (MN4-91-6) and soluble class I binding was detected using a biotinylated mAb reactive with a monomorphic region of the rat MHC class I molecule (OX18) followed by a streptavidin-alkaline phosphatase conjugate and substrate. The intra- and interassay variations were typically less than 5% and 10% respectively, to give a working range for the assay of between 62.5 and 1000 units/ml. Mitogenic stimulation led to a progressive increase in soluble class I levels in culture supernatants. This assay will be valuable in differentiating recipient and graft responses following experimental organ transplantation.

Animals↗

PubMed2005

An MHC class Ib-restricted TCR that cross-reacts with an MHC class Ia molecule.

TCR transgenic 6C5 T cells recognize an insulin B chain epitope presented by the nonclassical class I MHC molecule, Qa-1(b). Positive selection of these T cells was shown previously to require Qa-1(b). Despite dedicated specificity for Qa-1(b), evidence presented in the current study indicates that 6C5 T cells can cross-recognize a classical class I molecule. Clonal deletion was observed unexpectedly in 6C5.H-2(bxq) mice, which do not express I-E MHC class II molecules and thus should not be subject to superantigen-mediated negative selection. 6C5 T cells were observed to respond in vivo and in vitro to spleen cells from allogeneic H-2(q) mice, and specificity was mapped to D(q). Evidence was obtained for direct recognition of D(q), rather than indirect presentation of a D(q)-derived peptide presented by Qa-1(b). Polyclonal CD8(+) T cells from class Ia-deficient K(b)D(b-/-) mice reacted in vitro to allogeneic spleen cells with an apparent frequency comparable to conventional class Ia-restricted T cells. Our results provide a clear example of a Qa-1-specific TCR that can cross-react with a class Ia molecule and evidence supporting the idea that this may be a common property of T cells selected by class Ib molecules.

Animals↗

PubMed1999

Stochastic acquisition of Qa1 receptors during the development of fetal NK cells in vitro accounts in part but not in whole for the ability of these cells to distinguish between class I-sufficient and class I-deficient targets.

Fetal mouse NK cells are grossly deficient in the expression of Ly49 molecules yet show a limited ability to distinguish between wild-type and MHC class I-deficient target cells. In this paper we report that during their development in vitro from immature thymic progenitors, a proportion of C57BL/6 fetal NK cells acquires receptors for a soluble form of the nonclassical class I molecule Qa1b associated with the Qdm peptide, but not for soluble forms of the classical class I molecules Kb and Db. The acquisition of these Qa1 receptors occurs in a stochastic manner that is strictly controlled by cytokines, and in particular is strongly inhibited by IL-4. All fetal NK clones tested, including those that lack detectable Qa1 receptors, express mRNA for CD94 and for both inhibitory and noninhibitory members of the NKG2 family. Fetal NK cells lacking receptors for Qa1 (and also for classical class I molecules) cannot distinguish between wild-type and class I-deficient blasts but, surprisingly, distinguish efficiently between certain wild-type and class I-deficient tumor cells. A variant line that lacks several members of the NKG2 family kills both types of tumor cell equally well, suggesting the existence of NKG2-containing inhibitory receptors that recognize as yet undefined nonclassical class I molecules of restricted distribution.

Animals↗

PubMed1991

Defective HLA DRA X box binding in the class II transactive transcription factor mutant 6.1.6 and in cell lines from class II immunodeficient patients.

6.1.6 is one of several immunoselected mutants from EBV-transformed human B cell lines that have undergone coordinate loss of expression of all their HLA class II genes. Similar defects have been found in cells from some patients with class II immunodeficiencies. Previous studies have suggested that the defects in 6.1.6 and in the other class II regulatory mutants are in transactive factors required for class II transcription. The defective factors, however, have not been identified. Here we present two lines of evidence that serve to localize the site of action of the factor that is defective in 6.1.6. First, transfected indicator genes linked to HLA DRA promoter fragments that include the conserved X box region are transiently expressed at greatly reduced levels in 6.1.6, compared with the progenitor cell line T5-1. Second, a DNA-protein complex, termed X-A, formed by nuclear extracts from T5-1 with DRA sequences containing the X box and a few bases 5' and 3' to it, is missing with extracts from 6.1.6. Extracts from some but not all patients with class II-negative immunodeficiency also fail to form X-A, whereas extracts from class II-negative mutants derived from the Burkitt's line Raji do form an apparently normal X-A complex. The X-A complex contains proteins of approximately 22, 32, 82, and 92 kDa that can be cross-linked to a 5-bromodeoxyuridine-substituted X box probe by UV light. A defect in an X box-binding protein, or in a factor required for its binding, is a likely cause for the loss of transcription of the class II genes in 6.1.6.

Cell Line↗

PubMed1989

Asymmetry in the recognition of antigen: self class II MHC and non-self class II MHC molecules by the same T-cell receptor.

One of the most puzzling observations in immunology is the very high frequency of T cells reactive to non-self MHC molecules. Earlier studies from our laboratory suggested that the same receptor on a cloned T-cell line recognized both self-class II MHC: antigen complexes and non-self class II MHC, the latter at a significantly lower affinity. This suggested that alloreactivity resulted from low affinity cross-reactions of the T-cell receptor to a ligand presented at high multiplicity. The present studies address the question of whether these two ligands are recognized symmetrically by this receptor, and of whether different subsites in the receptor recognize both classes of ligands equally. In the present studies, we have greatly extended our analysis of T-cell receptor recognition of antigen: self class II MHC and non-self class II MHC. Using Fab fragments of monoclonal anti-T-cell receptor antibodies as monovalent competitive antagonists of T-cell activation, the response of cloned H-2k T-cell line D10 to conalbumin: I-Ak and to the allogeneic ligands I-Ab,v,p,q was analyzed with monoclonal antibodies directed at 3 clonotypic epitopes and one on V beta. These studies confirmed our earlier finding that D10 activation by antigen: self class II MHC is more difficult to inhibit with clonotypic Fab fragments binding to three distinct clonotypic epitopes than are responses to non-self MHC. More importantly, the Fab fragment of anti-V beta monoclonal antibodies preferentially inhibit activation by antigen: self class II MHC, and do so more efficiently than expected, based on the numbers of molecules of Fab bound.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Relationship among function, phenotype, and specificity in primary allospecific T cell populations: identification of phenotypically identical but functionally distinct primary T cell subsets that differ in their recognition of MHC class I and class II allodeterminants.

The goal of the present study was to evaluate the relationship among function, Lyt phenotype, and MHC recognition specificity in primary allospecific T cell populations. By using Lyt-2+ and L3T4+ T cells obtained from the same responder populations, we assessed the ability of T cells of each phenotype to generate cytotoxic effector cells (CTL) and IL 2-secreting helper T cells in response to either class I or class II MHC allodeterminants. It was found that a discordance between Lyt phenotype and MHC recognition specificity does exist in primary allospecific T cells, but only in one T cell subpopulation with limited functional potential: namely, Lyt-2+ T cells with cytotoxic, but not helper, function that recognize class II MHC alloantigens. Target cell lysis by these Lyt-2+ class II-allospecific CTL was inhibited by anti-Ia monoclonal antibodies (mAb), but not anti-Lyt-2 mAb, indicating that they recognized class II MHC determinants as their "restriction" specificity and not as their "nominal" specificity even though they were Lyt-2+. A second allospecific T cell subset with limited functional potential was also identified but whose Lyt phenotype and MHC restriction specificity were not discordant: namely, an L3T4+ T cell subset with helper, but not cytotoxic, function specific for class I MHC allodeterminants presented in the context of self-Ia. Thus, the present study demonstrates that primary allospecific T cell populations contain phenotypically identical subpopulations of helper and effector cells that express fundamentally different MHC recognition specificities. Because the recognition specificities expressed by mature T cells reflect the selection pressures they encountered during their differentiation into functional competence, these findings suggest that functionally distinct but phenotypically identical T cell subsets may be selected independently of one another during ontogeny. Thus, the existence of Lyt-2+ CTL specific for class II allodeterminants can be explained by the hypothesis that the association of Lyt phenotype with MHC recognition specificity results from the process of thymic selection that these Lyt-2+ effector cells avoid.

Animals↗

PubMed1985

Surface markers of T cells causing lethal graft-vs-host disease to class I vs class II H-2 differences.

Information was sought on the phenotype of lymphoid cells causing lethal graft-vs-host disease (GVHD) in irradiated mice expressing whole or partial H-2 differences. In all strain combinations tested, pretreating donor lymph node (LN) cells with anti-Thy-1 monoclonal antibodies (MAb) plus complement (C) abolished mortality. With GVHD directed to class I H-2 differences, pretreating LN cells with anti-Lyt-2 MAb prevented mortality, whereas MAb specific for Ly-1 or L3T4 cell surface determinants caused severe mortality. These data imply that lethal GVHD directed to class I H-2 differences is mediated by L3T4-, Lyt-2+ cells; this subset of T cells was shown previously to control GVHD directed to multiple minor histocompatibility antigens, i.e., antigens seen in the context of self-class I molecules. With whole H-2 differences, GVHD appeared to be controlled largely but not exclusively by L3T4+, Lyt-2-T cells. This T cell subset was also the predominant cause of GVHD directed to class II differences. With class II incompatibilities, depleting donor cells of L3T4+ T cells, either by pretreatment with anti-L3T4 MAb + C or by fluorescence activated cell sorter selection, greatly reduced but did not completely abolish GVHD. These data might imply that L3T4-, Lyt-2+ cells have some capacity to elicit anti-class II GVHD. A more likely possibility, however, is that the residual GVHD to class II differences observed with Lyt-2+-enriched cells reflected minor contamination with L3T4+ cells.

Animals↗

PubMed1995

Efficient internalization of MHC class II-invariant chain complexes is not sufficient for invariant chain proteolysis and class II antigen presentation.

In Ag-presenting cells, MHC class II molecules bind antigenic peptides in endocytic compartments and transport them to the cell surface for presentation to CD4+ T cells. Newly synthesized class II alpha beta heterodimers associate with a third polypeptide, invariant chain (Ii), in the endoplasmic reticulum. This association may prevent class II molecules from binding peptides until they are transported to endocytic compartments where Ii is proteolyzed. Signals in the Ii cytosolic tail are believed to be responsible for the targeting of class II-Ii complexes to endocytic compartments, but it is unclear whether this targeting event occurs at the trans face of the Golgi or at the plasma membrane. In this report, we address whether the endosomal localization signal in the Ii cytosolic tail can be functionally substituted with a tyrosine-based signal for rapid internalization from the cell surface. A chimeric protein was generated in which the Ii cytosolic tail was replaced in its entirety with the cytosolic tail from transferrin receptor. In cells expressing this chimeric form of Ii, newly synthesized class II-Ii complexes travel rapidly to the cell surface and are internalized efficiently, but Ii proteolysis is delayed and class II Ag presentation is inhibited. These results suggest that targeting class II-Ii complexes to early/recycling endosomes from the cell surface does not in itself lead to Ii proteolysis; subsequent delivery to later endosomes may be required. The data suggest that signals for this targeting event may lie in residues 18 to 29 of the Ii cytosolic tail.

Amino Acid Sequence↗

PubMed1993

Selective loss of human leukocyte class I allospecificities and staining of melanoma cells by monoclonal antibodies recognizing monomorphic determinants of class I human leukocyte antigens.

Immunoperoxidase staining of frozen sections from surgically removed melanoma lesions showed that anti-human leukocyte antigen (HLA)-A2, A28 monoclonal antibody (mAb) stained keratinocytes, but did not stain melanoma cells in 21% of the 14 primary and 44% of the 9 metastatic lesions tested. The loss of HLA-A2 and/or A28 allospecificities did not affect the staining patterns with mAb recognizing monomorphic determinants of HLA Class I antigens, in terms of percentage of stained melanoma cells and intensity of staining. This finding is not likely to reflect the sensitivity of the immunoperoxidase technique, since cytofluorographic analysis detected no significant difference in the staining pattern by mAb to monomorphic determinants of HLA Class I antigens between a melanoma cell line and an autologous transfectant that had acquired HLA-A2 antigens following gene transfer. The results of the present study imply that the frequency of abnormalities in HLA Class I antigen expression by melanoma cells is higher than that described in the literature, since selective losses of HLA Class I allospecificities are not detected by staining of melanoma cells with mAb to monomorphic determinants of HLA Class I antigens. The latter reagents have been used in most of the published studies to characterize the expression of HLA Class I antigens in melanoma lesions. Furthermore, the present results provide a mechanism for the unexpected resistance to cytotoxic T-cell-mediated lysis and the unexpected poor clinical course of the disease in some patients despite a high expression of HLA Class I antigens as measured by staining of melanoma cells with mAb to monomorphic determinants.

Antibodies, Monoclonal↗

PubMed1994

MHC class II-bound self-peptides can be effectively separated by isoelectric focusing and bind optimally to their MHC class II restriction elements around pH 5.0.

More than 90% of the major histocompatibility complex (MHC) class II molecules on antigen-presenting cells (APC) have in their binding site a peptide derived from an extracellular protein ingested by the APC or from a protein of the APC itself. These self-peptides can be eluted from affinity-purified MHC class II molecules by acid elution, and have been studied with a variety of techniques. We show here that the self-peptides eluted from the mouse MHC class II molecules Ad, Ed and Ek bind specifically to MHC class II molecules of the allelic type from which they were derived. The pH optimum for binding is around 5.0, i.e. the same optimum at which synthetic peptides representing sequences of foreign antigens bind to MHC class II molecules. This suggests that the physiological compartment where MHC class II molecules bind self-peptides may be very late in the endocytic pathway. The chemical properties of the eluted and labelled MHC class II peptides were studied by isoelectric focusing. This method was able to separate the peptides very efficiently, and enabled a rapid comparison of peptides eluted from different MHC molecules. The 125I-labelled peptides displayed a broad range of isoelectric points with values predominantly below neutral. This suggests that such peptides bind to MHC in a predominantly non-charged state.

Amino Acid Sequence↗

PubMed1996

Apoptosis-independent retinoblastoma protein rescue of HLA class II messenger RNA IFN-gamma inducibility in non-small cell lung carcinoma cells. Lack of surface class II expression associated with a specific defect in HLA-DRA induction.

Work from our laboratory indicates that HLA class II induction by IFN- gamma in the retinoblastoma (RB) protein-defective breast carcinoma line MDA-468-S4 (S4) requires reconstitution of functional RB. To determine whether RB is required for HLA class 11 expression in multiple tumor types, the RB-defective non-small cell lung carcinoma line H2009 and its RB-reconstituted subclones were examined for class II inducibility. Surface HLA-DR (DR) was not inducible by IFN-gamma in H2009. However, unlike the RB-reconstituted subclones of S4, DR surface expression was not detected in the H2009 RB-positive subclones. IFN-gamma induction of CIITA, a major regulator of class II transcription, suggested that H2009 retained at least part of the IFN-gamma signaling pathway leading to class II expression. Examination of class II mRNA indicated that IFN-gamma induction of RB was rescued in the RB-positive subclones of H2009, confirming the requirement for RB for HLA class II inducibility and revealing that RB is required for inducibility in developmentally distinct tumor types. However, DRA inducibility was not rescued in the H2009 RB-positive subclones, which explained the lack of surface DR induction in the RB-positive H2009 subclones. DPA and DPB were also only weakly inducible in the RB-reconstituted H2009 subclones, compared with the previously described, S4 RB-positive subclones. Finally, data reported here indicates that RB's ability to inhibit IFN-gamma-induced apoptosis is not a viable explanation for why RB expression rescues DRB inducibility in H2009.

Apoptosis↗

PubMed1996

MHC class I-processed pseudogenes in New World primates provide evidence for rapid turnover of MHC class I genes.

The MHC class I genes of the New World primate, the cotton-top tamarin (Saguinus oedipus), are an exception to the high polymorphism and variability displayed by this multigene family. We report the isolation of the first two processed pseudogenes from the MHC region in primates. These two MHC class I-processed pseudogenes (MHC-PS1 and -PS2) were found in several species of New World primates, suggesting a possible explanation for the cotton-top tamarin's limited MHC class I diversity. The pattern of synonymous and nonsynonymous substitutions in PS1 suggests that the gene that gave rise to this processed pseudogene was once subject to selection for variability in the peptide binding region and might, therefore, have been functional. Additionally, PSI is not closely related to the expressed cotton-top tamarin's MHC class I genes, but does show some similarity to So-N1, a tamarin pseudogene from which no transcript has been found. Thus, PS1 may represent a remnant of a once active MHC class I gene that is no longer functional in the cotton-top tamarin. The MHC class I loci in primates, therefore, appear to be evolving by a continual process of duplication and inactivation. This process seems to be exaggerated in New World primates and may in part be responsible for the cotton-top tamarin's limited MHC class I diversity.

Animals↗

PubMed1997

Characterization of transport of newly assembled, T cell-stimulatory MHC class II-peptide complexes from MHC class II compartments to the cell surface.

In human B cells MHC class II molecules acquire antigenic peptides in lysosome-related compartments called the MHC class II compartments (MIIC). How assembled complexes, capable of activating T cells, then reach the cell surface has not been fully resolved. We have used selective ablation of early and recycling endosomes to determine whether newly peptide-loaded class II molecules require functional recycling endosomes to exit to the cell surface. Cellular compartments accessed by transferrin-horseradish peroxidase conjugates were functionally inactivated by cross-linking with diaminobenzidine and hydrogen peroxide. Cells with ablated endosomal compartments were unable to recycle transferrin to the cell surface and could not deliver exogenous Ag for processing and presentation to T cells. In contrast, cells that had taken up Ag and assembled intracellular class II-peptide complexes before endosome ablation were still able to deliver class II-peptide complexes to the cell surface and stimulate T cell proliferation. This delivery was abolished in the presence of brefeldin A. These data show that the parts of the endocytic apparatus necessary for Ag delivery to the MIIC are not required for functional class II-peptide complexes to reach the cell surface. Moreover, the brefeldin A sensitivity of this final step in the class II molecule biosynthetic pathway suggests a vesicular intermediate for transport between the MIIC and the plasma membrane.

B-Lymphocytes↗

PubMed1997

Major histocompatibility complex (MHC) class II--positive dendritic cells in the rat iris. In situ development from MHC class II-negative precursors.

PURPOSE: To examine the postnatal development of major histocompatibility complex (MHC) class II-positive dendritic cells (DC) in the iris of the normal rat eye. METHODS: Single- and double-color immunomorphologic studies were performed on whole mounts prepared from rat iris taken at selected postnatal ages (2 to 3 days to 78 weeks). Immunopositive cells were enumerated, using a quantitative light microscope, and MHC class II expression on individual cells was assessed by microdensitometric analysis. RESULTS: Major histocompatibility class II-positive DCs in the iris developed in an age-dependent manner and reached adult-equivalent density and structure at approximately 10 weeks of age, considerably later than previously described in other DC populations in the rat. In contrast, the anti-rat DC monoclonal antibody OX62 revealed a population of cells present at adult-equivalent levels as early as 3 weeks after birth. Dual-color immunostaining and microdensitometric analysis demonstrated that during postnatal growth, development of the network of MHC class II-positive DCs was a consequence of the progressive increase in expression of MHC class II antigen by OX62-positive cells. CONCLUSIONS: During postnatal growth, the DC population of the iris develops initially as an OX62-positive-MHC class II-negative population, which then develops increasing MHC class II expression in situ and finally resembles classic DC populations in other tissue sites. Maturation of the iris DC population is temporally delayed compared with time to maturation in other tissue sites in the rat.

Animals↗

PubMed1998

Examination of serum class I antigen in allograft recipient rats--origin and control of serum class I antigen.

We examined the appearance of DA type (RT1Aa) class I antigen in the serum of rats that had received isogeneic or allogeneic liver grafts (DA into DA, DA into LEW, PVG into DA, PVG into F1 hybrid (DAxPVG). Recipient LEW rats were given either one injection of the anti-CD8 mAb, OX-8, following thymectomy or anti-CD4 mAb (cocktail of OX-35 and OX-38) following thymectomy 3 days prior to liver grafting. We also tested the serum RT1Aa antigen titer of F1 (DAxPVG) recipients after PVG spleen transplantation and the serum RT1Aa antigen titer in the DA rat after hepatectomy and cyclosporin treatment. Replacement of DA liver by PVG lowered transiently the serum level of RT1Aa antigen to 70% of that in normal DA serum shortly after liver transplantation. However, this titer increased gradually over the level in normal DA serum. A PVG spleen graft to an F1 hybrid recipient resulted in death due to typical GVH disease between 13 and 24 days after spleen transplantation. The RT1Aa antigen titer increased to several times more than that in normal F1 serum throughout the observation period. LEW recipients of DA liver died at 9-11 days (9.8 +/- 1.1 days) due to acute liver rejection. In this combination, the serum level of RT1Aa increased until day 8, reaching a maximum (four times) on day 4. Deletion of either CD8+ or CD4+ T cells by anti-CD8 or anti-CD4 MAb in this transplantation prolonged the survival times of liver grafts for up to 26.8 +/- 8.4 and 35.6 +/- 17.9 days, respectively. In the anti-CD8 or anti-CD4 MAb- treated recipients, the serum titer of DA class I antigen was not elevated and there were no differences between the two. Hepatectomy in combination with cyclosporin induced a higher titer of liver-derived class I antigen in the serum as long as liver regeneration proceeded. These results suggest that the liver is the principal source of serum class I antigen in rats. Rejection, GVH reaction and liver regeneration increased the serum class I antigen from transplanted liver or host tissue. It is unlikely that this is due to cleavage of membranous class I antigen by class I- reactive CD8+ T cells.

Animals↗

PubMed1999

Class II-associated invariant chain peptide-independent binding of invariant chain to class II MHC molecules.

The class II-associated invariant chain peptide (CLIP) region of invariant chain (Ii) is believed to play a critical role in the assembly and transport of MHC class II alphabetaIi complexes through its interaction with the class II peptide-binding site. The role of the CLIP sequence was investigated by using mutant Ii molecules with altered affinity for the DR1 peptide-binding site. Both high- and low-affinity mutants were observed to efficiently assemble with DR1 and mediate transport to endosomal compartments in COS cell transfectants. Using N- and C-terminal truncations, a region adjacent to CLIP within Ii(103-118) was identified that can complement loss of affinity for the peptide-binding site in mediating efficient assembly of alphabetaIi. A C-terminal fragment completely lacking the CLIP region, Ii(103-216), was observed binding stably to class II molecules in immunoprecipitation studies and experiments with purified proteins. The Ii(103-118) region was required for this binding, which occurs through interactions outside of the alphabeta peptide-binding groove. We conclude that strong interactions involving Ii(103-118) and other regions of Ii cooperate in the assembly of functional alphabetaIi under conditions where CLIP has little or no affinity for the class II peptide-binding site. Our results support the hypothesis that the CLIP sequence has evolved to avoid high-stability interactions with the peptide-binding sites of MHC class II molecules rather than as a promiscuous binder with moderate affinity for all class II molecules.

Amino Acid Sequence↗

PubMed1992

[The morphological relations of eugnathia and class-II/1 and class-III malocclusions to the changes in the topography of the cervical spine in the lateral teleroentgenogram].

Relations are discussed between malocclusions and changes of the vertebral spine. It was the aim of our investigations to disclose the causal relations between changes of the position of the cervical spine and class-II/1 anomalies (49 patients), class-III anomalies (28 patients), and eugnathic maxillary conditions (50 children). 127 lateral cephalograms of the untreated 63 boys and 64 girls at the age from six to 13 years were evaluated according to 24 orthodontic and 25 orthopedic characteristics. Patients with class-II/1 anomalies and class-III anomalies showed the tendency to strongly marked lordosis of the cervical spine. The basal angles nasion-tuberculum sellae-opisthion, nasion-tuberculum sellae-basion, and nasion-dorsum sellae-basion were enlarged in class-II/1 cases and reduced in class-III cases. It could not pointed out relations between the sagittal position of the jaws and the position of the atlas; there was no existing a specific bearing of the head within the various groups.

Adolescent↗

PubMed2002

Association of MHC class I and class II gene polymorphisms with vaccine or challenge response to Salmonella enteritidis in young chicks.

Salmonella enteritidis (SE) is a worldwide source of salmonellosis in humans, caused mainly by consumption of contaminated poultry products. The major histocompatibility complex (MHC) class I and class II molecules, which function as antigen-presentation structures, are involved in both macrophage and dendritic cell immune response to Salmonella and may, therefore, play an important role in host resistance to infections. The chicken MHC class I and class II were investigated as candidate genes for immune response to SE. We characterized the complete MHC class I cDNA sequences for an outbred broiler line and four diverse highly inbred lines: two MHC-congenic Leghorn (G-B2 and G-B1), one Egyptian Fayoumi (M15.2), and one Spanish (Sp21.1), to define the allelic sequences within these lines, so that we might study the association between particular MHC polymorphisms and response to SE. The F1 offspring of outbred broiler sires crossed with three inbred lines (G-B1, G-B2, and Fayoumi) were evaluated as young chicks for either bacterial load in spleen and cecum after pathogenic SE inoculation or antibody level after SE vaccination. Alleles defined by a Lys(148)-->Met(148) polymorphism in the MHC class I alpha(2) domain were associated with spleen bacterial load after SE challenge. These results suggest that particular MHC haplotypes may contribute to control of responses to SE, and that particular polymorphisms may serve as markers for genetic resistance to SE in the chicken.

Animals↗