Biomedical subjects

M Pierres

Publications and source records attributed to M Pierres.

At least 73 records · Page 4Linked to original sources

PubMed1984

Multiple functional sites on a single Ia molecule defined using T cell clones and antibodies with chain-determined specificity.

Monoclonal antibodies (mAb) were used to inhibit the proliferation of antigen-reactive (C57BL6/J X A/J)F1 restricted T cell clones. We have been able to subdivide these F1 restricted T cell clones into two groups: one of which recognizes the A alpha k A beta b molecule and the other group which recognizes the A alpha b A beta k molecule. Using clones with defined reactivities, we could assign the reactivities of monoclonals to the A alpha or A beta chains. By immunoprecipitation and two-dimensional analysis of Ia molecules from F1 spleen cells, we could independently map the reactivities of the mAb as being determined by the A alpha or A beta chain. To date, these two methods of chain localization of the antibody reactivity have agreed. Further, the differential blocking of the A alpha k A beta b restricted T cell clones suggests that there exists more than one restriction site per Ia molecule. Increasing the number of possible functional Ia restriction sites, either through combinatorial association of alpha and beta chains or by using more than one site per molecule, should increase the number of ways Ia molecules can function in antigen presentation.

Animals↗

PubMed1984

Efficiency of antigen presentation to T cell clones by (B cell X B cell lymphoma) hybridomas correlates quantitatively with cell surface ia antigen expression.

A series of B cell hybridomas was used as a model system to assess quantitatively the role of Ia molecules in antigen presentation to allo- or soluble antigen-reactive T cell clones. These hybrid cell lines were established by fusion between the HGPRT-BALB/c B cell lymphoma M12.4.1 and LPS-stimulated spleen blasts from B10.BR (H-2k) mice. Quantitative cellular absorption of appropriate anti-Ia monoclonal antibodies and flow cytofluorometric analyses revealed that the B cell hybridomas examined herein expressed constitutively a number of surface I-Ak or I-Ek molecules that varied in an order of magnitude of 1 to 5. Such quantitative differences could be correlated precisely with (a) the capacity of B cell hybridomas to activate T cell clones to proliferate and/or to produce interleukin 2 in response to E beta k allodeterminant or to poly(Glu60Ala30Tyr10) presented in the context of I-Ak restriction element, and (b) the amount of monoclonal anti-I-Ak antibody required to inhibit antigen presentation to T cell clones. The possible implications of these data are discussed in the context of current models of regulation of Ia antigen expression by antigen-presenting cells.

Animals↗

PubMed1984

Gene transfer of H-2 class II genes: antigen presentation by mouse fibroblast and hamster B-cell lines.

We have transferred the mouse Ak alpha and Ak beta genes, which encode the class II I-Ak molecule, into mouse L-cell fibroblasts and hamster B cells. I-Ak molecules are expressed on the surface of both cell types. The L-cell and hamster B-cell I-Ak molecules appear normal by serological analyses and two-dimensional gel electrophoresis. Furthermore, the I-Ak molecules on L cells can act as targets for the allogenic T-cell killing of the transformed L cells. The I-Ak molecules in both mouse fibroblasts and hamster B cells can present certain antigens to T-cell helper hybridomas. Thus only class II molecules are required to convert the nonantigen-presenting cell. Accordingly, it will be possible to dissect the structure-function relationships existing between Ia molecules, foreign antigen, and T-cell receptor molecules by in vitro site-directed mutagenesis and gene transfer.

Animals↗

PubMed1984

Rat monoclonal antibodies to mouse IgG1, IgG2a, IgG2b, and IgG3 subclasses, and kappa chain isotypic determinants.

Rats of the LOU/Ws1 strain were immunized with mixtures of mouse monoclonal antibodies (MAbs) of various isotypes, and their spleen cells were fused with the rat myeloma Y3.Ag1.2.3 or the mouse myeloma X63.Ag8.653. From four fusion experiments, we have selected 14 rat MAbs that exhibited selective binding to either IgG2a, IgG2b, IgG1, and IgG3 subclasses or to kappa chain isotypic determinants. Cross-blocking studies revealed that three rat MAbs identified distinct determinants on the Fc fragment of the MAb H10-81.10 (A.TH, Igh-1e). By contrast, the IgG1, IgG2b, IgG3, and kappa isotypes defined by the mAbs analyzed in this study were found to be in close spatial relationship. These rat MAbs bound IgG2a, IgG2b, or IgG1 mouse MAbs, expressing the Igh-1e,j,a, or c, Igh-3a or b, or Igh-4a or b allelic specificities, respectively.

Animals↗

PubMed1984

Shared idiotope on monoclonal anti-Ia.7 antibodies reactive with determinants in a structural domain of the I-E molecules.

In previous studies, heterologous anti-idiotypic (anti-Id) antisera against the C3H.SW 14-4-4S or the A.TH 41.A anti-Ia.7 monoclonal antibodies (mAb) were shown to identify an interstrain cross-reactive idiotypic specificity (IdX.Ia.7) expressed on monoclonal or conventional anti-Ia.7 alloantibodies. The objective of the present investigation was to characterize further this IdX at the idiotopic level. To this end, 11 hybridomas producing IgG1, IgG2a, or IgM anti-Id mAb were derived from a rat immunized with a mixture of 10 A.TH or A.BY anti-Ia.7 mAb. The specificity of the latter anti-Id mAb was determined by direct Id binding radioimmunoassay (RIA) with the use of a panel of 52 anti-Ia mAb derived from hybridomas produced in various inbred mouse strains. These rat anti-Id mAb recognized idiotopes expressed on i) all anti-Ia.7 mAb against determinants in the topographic domain I of the I-Ek molecule but not on 18 other anti-I-Ek mAb directed at epitopes in domains II or III; ii) three of 19 anti-I-Ak mAb; and iii) one A.TL-derived anti-I-As mAb. Competitive Id binding assays revealed that among the 14 IdX+ anti-Ia.7 mAb, one (81.B) was bound to a lesser extent by various rat anti-Id mAb, suggesting that heterogeneity probably exists in this antibody family. By contrast, two isologous (B10.S(7R)) anti-Id mAb to the IdX.Ia.7+ mAb 41.A displayed a specificity restricted to 41.A individual idiotopes (IdI). Rat anti-IdX.Ia.7 and mouse anti-41.A IdI mAb inhibited the binding of 125I-labeled mAb 41.A to CBA spleen cells. These two sets of mAb bound in a noncompetitive fashion to mAb 41.A-coated plates, indicating that their corresponding public or private idiotopes were spatially distinct. These data may have implications for in vivo manipulations of anti-Ia immune responses.

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PubMed1984

A rat anti-mouse T4 monoclonal antibody (H129.19) inhibits the proliferation of Ia-reactive T cell clones and delineates two phenotypically distinct (T4+, Lyt-2,3-, and T4-, Lyt-2,3+) subsets among anti-Ia cytolytic T cell clones.

Hybridoma H129 .19 was derived by fusion between spleen cells of a Lou / Ws1 rat immunized with an Lyt-1+,2- anti-I-Ak cytolytic T lymphocyte (CTL) clone and the nonsecreting myeloma X63-Ag8.653. The monoclonal antibody (mAb) H129 .19 (IgG2a, kappa) was selected for its capacity to inhibit the lytic potential of the immunizing clone. H129 .19 identified a monomorphic determinant on a 55 m.w. murine T cell differentiation antigen, which appeared to be homologous to the human T4 molecule in that: 1) H129 .19 reacted with 80% adult thymocytes, with a subset of splenic T cells, and with the interleukin 2 (IL 2)-producing EL4 thymoma; 2) The mAb bound to and inhibited the IL 2 production and the proliferation of various allo- or soluble antigen-reactive T cell clones that recognized restriction or activating determinants on the I-A or I-E molecules, respectively; 3) H129 .19 did not inhibit the proliferation and/or cytolysis of Lyt-2,3+ T cells specific for class I MHC antigen; and 4) Among six anti-Iak CTL clones examined in this study, the mAb H129 .19 reacted with two I-Ak-specific, Lyt-2,3- clones on which it exerted strong cytolysis inhibiting effect at the effector cell level. By contrast, two other anti-I-Ak and two anti-I-Ek CTL clones were found to express the Lyt-2,3+,T4- cell surface phenotype. The cytolytic potential of the latter clones was not inhibited by anti-Lyt-2,3 mAb. These studies strongly suggest that the mouse T4 molecule facilitates the recognition of class II MHC antigen by most but not all T cells.

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PubMed1984

An analysis of functional T cell recognition sites on I-E molecules.

The recognition of I-E molecules by antigen-specific T cells was studied to determine if one or multiple topographic sites on the I-E molecules can function as restricting elements for T cells. A panel of 14 I-Ek-specific monoclonal antibodies (mAb) was used to inhibit T cell proliferation induced by antigens, the recognition of which was restricted by I-E-encoded determinants. These antibodies gave patterns of inhibition that were similar for three long-term antigen-specific T cell lines. Multiple distinct patterns of inhibition, however, were observed when a series of antigen-specific I-E-restricted T cell clones was studied. Differences were identified even among clones expressing apparently similar antigen specificities and MHC restriction. The observed inhibition by these antibodies appeared to be caused by specific steric or allosteric interference with T cell recognition of antigen and Ia. Based on the differences in patterns of inhibition, it was possible to infer the existence of distinct sites or conformations on the I-E molecule that are functionally involved in antigen-specific T cell recognition.

Animals↗

PubMed1984

The structure-function relationship of I-A molecules: correlation of serologic and functional phenotypes of four I-Ak mutant cell lines.

We have isolated and characterized four mutant I-Ak-expressing cell lines derived from the B cell-B lymphoma hybrid antigen-presenting cell line TA3. The mutants were isolated by first selecting against expression of one Ak epitope by treatment with a monoclonal antibody in the presence of complement and then selecting for retention of a second Ak epitope by electronic cell-sorting of cells stained for fluorescence with a second monoclonal antibody. The serologic and functional phenotypes of the mutants were characterized by using panels of I-Ak-specific monoclonal antibodies and I-Ak-restricted T hybridomas. We obtained one Ak alpha mutant (J4) that no longer reacts with any Ak alpha-specific antibody and also is incapable of stimulating any I-Ak-restricted T hybridoma. We obtained three Ak beta mutants (LD3, K5, G1) that express a wide range of serologic and functional phenotypes. Correlation of the serologic and functional phenotypes reveals that the serologic epitope Ia.1 may overlap with a major site of T cell recognition, whereas the Ia.17 serologic epitope appears to be only a minor site for T cell recognition.

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PubMed1984

The role of I-A/E molecules in B lymphocyte activation. I. Inhibition of lipopolysaccharide-induced responses by monoclonal antibodies.

A panel of 22 different monoclonal antibodies, including specificities against various antigenic clusters of I-A and I-E molecules, were probed over a wide range of concentrations for their ability to inhibit lipopolysaccharide-induced B lymphocyte proliferation and maturation to immunoglobulin-secreting plaque-forming cells (PFC). Most antibodies were competent to inhibit up to 80 to 100% of the response of appropriate target cells, although having little or no effect on irrelevant spleen cell cultures. Mixtures of either anti-I-A or anti-I-E specificities were more efficient inhibitors than individual antibodies, as shown by the average concentrations required for 50% inhibition (30 and 300 ng/ml, respectively). The selective role of I-A/E molecules in B cell activation was demonstrated by the failure of anti-K antibodies of the same isotype, bound in comparable amounts to target cells, to modulate B cell responses in parallel cultures. Fc receptor-mediated inhibitory effects were further excluded by equivalent inhibition obtained with anti-I-A antibodies of the IgM class. Anti-I-A/E antibodies appear to inhibit the inductive phase of B cell responses, as suggested by limiting dilution experiments performed in the presence of 50% inhibitory concentrations of antibodies: 50% of the control number of reactive clones were found to respond, but those that escaped inhibition developed to control sizes of progenies producing PFC.

Animals↗

PubMed1983

Expression of Ia antigens by cultured astrocytes treated with gamma-interferon.

The expression of major histocompatibility complex class II or Ia antigens by neural cells has been investigated by indirect immunofluorescence on dissociated cultures from mouse cerebellum, cerebral cortex and dorsal root ganglia. Ia antigen expression was not detectable under standard culture conditions. However, treatment of mixed cultures from the cerebellum and of astrocyte cultures from the cerebral cortex with gamma-interferon preparations induced expression of Ia antigens on a fraction of the astrocytes. Under the same conditions, Ia+ cells could be observed in dorsal root ganglion cultures.

Animals↗

PubMed1983

Distinct HLA-DR epitopes and distinct families of HLA-Dr molecules defined by 15 monoclonal antibodies (mAb) either anti-DR or allo-anti-Iak cross-reacting with human DR molecule. I. Cross-inhibition studies of mAb cell surface fixation and differential binding of mAb to detergent-solubilized HLA molecules immobilized to a solid phase by a first mAb.

A series of HLA-DR-reactive mouse anti-human B cell or anti-Ia monoclonal antibodies (mAb) have been used to explore the serological complexity of human class II antigens at the determinant level, using two techniques: (a) cross antibody-binding competitor assays using 125I-labeled and-unlabeled mAb were performed to study the topological organization of the corresponding determinants to determine epitopic clusters recognized by this collection of mAb and (b) differential reactivity of mAb to detergent-solobilized solid-phase-immobilized HLA-DR molecules to determine epitopes expressed on identical DR isotypes. The fifteen mAb could be classified according to the first technique as falling into three different epitopic clusters. Using the second technique, we were able to define at least two independent molecular subsets, one co-expressing two of the three epitopic clusters and the second expressing only the third one. We could not formally identify molecular subsets expressing only one of the first two clusters, using the second technique. The precise serological mapping of the determinants recognized by various anti-class II mAb should prove very useful if such mAb were to be introduced in anti-class II-specific T cell clone blocking experiments. We anticipate that some of them should facilitate the correlation at the clonal level between the T cell repertoire and the epitopes or molecular subsets defined by these mAb. However, within mAb belonging apparently to a same cluster, some could mediate different biological effects.

Animals↗

PubMed1983

T cell-mediated cytolysis: on the strength of effector-target cell interaction.

Allosensitized lymphoid cell populations contain T lymphocytes that can bind to target cells and lyse them. We asked whether there was a relationship between lymphocyte target cell-binding strength and occurrence of cytolysis. Using graded shear forces to dissociate effector-target cell conjugates, we found that (a) within an allosensitized lymphoid cell population derived from an heterogeneous mixed leukocyte culture, there were lymphocyte-target cell conjugates with binding strengths differing by a factor of at least 10(2), (b) even the minimal force required to release a significant amount of bound target cells could disrupt the plasma membranes of some tumor cells and (c) these tumor cells disrupted by shear forces were probably part of cytolysis-conducive rather than of non-cytolysis-conductive conjugates. We combined this approach with the use of cytolysis-inhibiting monoclonal antibodies (mAb), and found that antibody-induced decrease of cytolysis was correlated with a decrease in the percentage of strong or total conjugates, depending on the mAb used. When lectins were added to overcome the inhibitory effect of the mAb, reappearance of cytolytic activity correlated with reappearance of conjugates. This was especially striking using wheat germ agglutinin (WGA): the addition of WGA to irrelevant effector-target cell combinations did not lead to cytolysis; however, the addition of WGA to relevant effector-target cell combinations inhibited by mAb led to reappearance of cytolysis and of strong conjugates. Taken together, these and other results suggested that under our experimental conditions a threshold level of binding strength between effector and target cells might be important, although not sufficient, for T cell-mediated cytotoxicity. These results were not inconsistent with the involvement of mechanical factors in this process. Also, they were in line with the concept of nonantigen-specific lymphoid cell surface interacting molecules, detected by the mAb used and important for the establishment of strong, functional lymphocyte target cell interactions. Finally, they underlined the necessity of a quantitative estimate of cell-cell binding strength when investigating the effect of a given agent (e.g. a mAb) on lymphocyte target cell recognition.

Animals↗

PubMed1983

Dissection of the Poly(Glu60Ala30Tyr10) (GAT)-specific T-cell repertoire in H-2Ik mice. II. The use of monoclonal antibodies to study the recognition of Ia antigens by GAT-reactive T-cell clones.

Twenty-five allospecific monoclonal antibodies (mAb), produced in the A. TH. A.BY, or B10.S (7R) anti-A.TL combinations, were shown to recognize determinants organized in four spatially distinct polymorphic regions on the same I-Ak-encoded molecule(s). These reagents were used to assess the recognition of the class II major histocompatibility complex (MHC) determinants in a series of GAT-reactive A.TL T-cell clones exhibiting various restriction specificity or alloreactivity patterns. Of the proliferative responses of 13 cloned T cells, 12 responses were found to be inhibited similarly by the same set of mAbs.A hierarchy in the blocking effects of these reagents that could be correlated with the spatial organization of their determinants was observed. (i) All the mAbs defining the epitope region I (i.e., recognizing public Ia.1- or Ia.17-like determinants, presumably expressed on the A beta subunit) and some of those identifying new public determinants in the epitope region II profoundly inhibited these T-cell responses. (ii) Intermediate blocking was observed when mAbs recognizing public determinants in the epitope region III were used. (iii) Finally, among the mAbs that identified the epitope group IV, the Ia.19-specific mAb 39.J was inhibitory, whereas mAbs directed against private Ia.2-like determinants were not. By contrast, the GAT-specific proliferative response of the T-cell clone AT-20.1, which recognized its nominal antigen in an extensively cross-reactive MHC-restricted fashion, could only be inhibited by a subset of the mAbs recognizing epitopes in groups I and II, but not by those recognizing epitopes in groups III and IV. It was also shown that the same subset of I-Ak-and I-Au-reactive mAbs displayed similar blocking effects on the proliferation of two T-cell clones exhibiting dual specificity for I-Ak- and I-Au-restricting and/or I-Ak- and I-Au-alloactivating determinants. Finally, all the cloned T-cell responses examined were found to be inhibited by rat mAbs against the LFA.1 molecule or the murine equivalent of the human OKT4 differentiation antigen. These studies suggest that class II specific mAbs can impair proliferation of cloned T-cells by a mechanism(s) other than the masking of the T-cells' restriction determinants per se.

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PubMed1983

Dissection of the poly(glu60 ala30 tyr10) (GAT)-specific T-cell repertoire in H-2Ik mice. I. GAT plus self-I-Ak-reactive T-cell clones can recognize alloactivating and/or restriction determinants on nonself-Ia molecules.

We examined the antigen recognition of the class II major histocompatibility complex (MHC) of 45 poly(glu60 ala30 tyr10) (GAT)-reactive T-cell clones isolated by limiting dilution cloning of a pool of in vivo-primed and in vitro-restimulated A.TL lymph-node T cells. Each clone expressed the Thy-1.2+, Lyt-1+, Lyt-2-, LFA-1+, Ia-, and H-2Dd+ cell-surface phenotype and exhibited strict specificity for GAT on syngeneic antigen-presenting cells (APCs). The monitoring of the proliferative responses of these clones in the presence or absence of GAT, using APCs from strains with 11 independent H-2 haplotypes, revealed several distinct specificity patterns: (i) most (31 of 45, 73%) T-cell clones recognized GAT in a self-I-Ak-restricted manner; (ii) other alloreactive clones (5 of 45, 11%) were stimulated to proliferate, irrespective of the presence of GAT, in response to allodeterminants expressed on H-2s, H-2d, H-2f or H-2u spleen cells; (iii) a third T-cell clone subset (4 of 45, 9%) was activated by GAT in the context of not only self-I-Ak but also nonself restriction Ia determinants; and (iv) three clones (7%) exhibited a triple specificity, i.e., they recognized GAT in the context of self and nonself Ia determinants and were alloreactive. One of the latter clones responded to GAT in an apparently non-MHC-restricted manner and recognized an I-Ab allodeterminant. These data provide direct evidence that the antigen-specific and alloreactive T-cell repertoires overlap and that the self-MHC restriction of GAT-specific T-cell responses is not absolute in A.TL mice.

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PubMed1983

Murine H-2Dd-reactive monoclonal antibodies recognize shared antigenic determinant(s) on human HLA-B7 or HLA-B27 molecules or both.

We have evaluated the serological relationships between the murine H-2Dd and human HLA molecules using four H-2Dd-reactive monoclonal antibodies (mAbs) produced in the A.BY (KbIbDb) anti-A.TL (KsIkDd) combination. In the mouse, these reagents exhibited three distinct reactivity patterns: Dd, Ks, and H-2u (mAb 81.L); Dd, H-2p, and H-2u (mAb 81.R); and Dd, Kd, H-2p, H-2u, and H-2v (mAbs 97.G and 97.H). Sequential immunoprecipitation and cross-competitive mAb binding experiments revealed that these mAbs recognized determinants in two spatially distinct polymorphic domains on the H-2Dd molecule of B10.A(5R) cells (defined by mAbs 81.L and 81.R, 97.H, and 97.G, respectively). MAbs 81.R, 97.G, and 97.H, but not 81.L, also defined an HLA-linked polymorphism in the human, the main characteristics of which can be summarized as follows: (i) on B lymphoblastoid cell lines, mAbs 81.R and 97.H bound to cells expressing the HLA-B7, HL-B27 or Bw40 cross-reacting specificities, (ii) on peripheral blood lymphocyte (PBL) panel mAb 81.R exerted C dependent cytotoxicity to 118 of 400 cells tested, including almost all HLA-B7 or HLA-B27 cells or both (r: 0.952), (iii) the expression of the 81.R cross-reacting determinant segregated in an informative family with the parental haplotype carrying the HLA-B7 allele, and (iv) mAbs 81.R, 97.G, and 97.H recognized topologically related determinants on the same class I molecule(s) of the human B lymphoblastoid cells JY (HLA-A2,2, -B7,7). These data support the view that some, but not all H-2Dd allotopes have been conserved throughout evolution and are associated in the human with the HLA-B7, -B27 cross-reacting specificities.

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PubMed1983

Mouse monoclonal anti-Ia antibodies recognize cross-reacting determinants expressed on distinct subsets of human Ia-like cell-surface molecules.

Human Ia-like cell-surface molecules from a homozygous HLA-DR (6/6) B lymphoblastoid cell line have been analyzed using five mouse anti-Ia m.Ab cross-reacting with HLA-DR antigens. The surface-iodinated molecules immunoprecipitated by these m.Ab were analyzed by SDS-PAGE under reducing conditions and by SDS-PAGE followed by isoelectrofocusing. As read from the different migration patterns, three distinct combinations of human Ia-like molecules were identified by these m.Ab. Three anti-I-E-reactive m.Ab immunoprecipitated two-chain molecules whose apparent mol. wt (32K, 29K) corresponded to those of the classical HLA-DR antigens. One m.Ab which on mouse cells recognized a determinant shared by the I-A and I-E molecules precipitated not only the 32-29K bands, but also a 26K band from human cell extracts. Finally, an I-A reactive m.Ab precipitated a complex set of polypeptides including in addition to the 32-29K bands, three additional chains of 30, 28 and 26K. Sequential immunoprecipitation demonstrated that removal of the classical 29-32K HLA-DR chains by an anti-I-E m.Ab did not affect the subsequent immunoprecipitation of the additional chains by the anti-I-A or the anti-I-A + I-E m.Abs. These patterns and those obtained by 2D-gels analysis which demonstrated the complexity of the 26K band are compatible with the coexpression of at least three different subsets of molecules: (1) Ia-like molecules of 29-32K, recognized by all the m.Ab used; (b) molecules of 28-30K recognized by the anti-I-A m.Ab and (c) molecules apparently constituted by 26K chains, precipitated by the anti-I-A m.Ab and by the anti-I-A + I-E m.Ab.

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PubMed1983

The importance of cross-reactions between species: mouse allo-anti-Ia monoclonal antibodies as a powerful tool to define human Ia subsets.

Three mouse allo-anti-Ia monoclonal antibodies recognizing epitopes specific for either I-E gene products (H81.98.21 and H40.315.7 Mabs) or shared between I-E and I-A gene products (H82.246.3 Mab) were used to analyze the human Ia molecules against which they cross-react. The results indicated that in the Ia pool of the human B cell line Raji the three Mabs were able to recognize at least three distinct subsets differing each other both in their alpha as well as in their beta subunits. The comparison with the previously defined human Ia subsets NG1, NGe, and DC1 suggested the following similarities: H81.98.21 specific Ia molecules similar to NG1; H82.246.3 specific Ia molecules similar to NG2, and including probably NG1; H40.315.7 specific molecules similar to DC1 in their alpha subunits and probably heterogeneous in their beta subunits with characteristics of the DC1, NG1, and NG2 subunits altogether. The heterogeneity of the human Ia molecules and the possible similarities with the mouse Ia system were discussed.

Animals↗

PubMed1983

A murine anti-I-Ak monoclonal antibody recognizes human DR (I-E-like) antigens.

A monoclonal antibody. H39-49.5, originally raised against the murine I-Ak antigen, recognizes a nonpolymorphic determinant on HLA-DR-like molecules from human cells. These HLA-DR-like molecules have been characterized by amino acid sequencing and have been found to be homologous to the murine I-E antigens rather than the murine I-A antigens. These results suggest a common origin for the murine I-E, I-A, and HLA-DR antigens and caution that serological cross-reactivity alone cannot be used to reliably establish the presence of structural homologues of I-E- or I-A-like molecules in other species.

Amino Acid Sequence↗