Femia Kievits

HLA-B27 as a relative risk factor in ankylosing enthesopathy in transgenic mice.

HLA-B27 is a risk factor for several human diseases through a mechanism that is not yet understood. This article describes a naturally occurring joint disease in laboratory mice, ANKENT. ANKENT begins with mild inflammation and culminates in irreversible stiffening of the ankle and/or tarsal joints in one or both hind paws. The macroscopic and histologic features of ANKENT, its relationship to age, gender, and environment, and some immunologic aspects are considered. With respect to genetics, it is demonstrated that an HLA-B27 transgene is a relative risk factor for ANKENT. Its impact depends on the H-2 haplotype, reaching a relative risk value of 9.4 for C57Bl/10, H-2b males (p < 0.025). Several features of ANKENT are reminiscent of human AS: joint pathology, age and gender distribution, the presence of non-MHC as well as MHC risk factors (including HLA-B27), and the suspicion that environmental factors are involved.

Monomorphic anti-HLA monoclonal antibody (W6/32) recognizes polymorphic H-2 heavy-chain determinants exposed by association with bovine or human but not murine ß2-microglobulin

W6/32 is a mouse anti-HLA class I monoclonal antibody (MoAb) of BALB/c (H-2d) origin with a monomorphic reaction pattern on human cells. In this study, we explain that the previously reported (Ivanyi D et al., Immunogenetics 20:6gg, 1984) cross-reactions of W6/32 with the H-2Db antigen are completely dependent on the formation of a complex between the H-2Db heavy chain with bovine beta 2-microglobulin (beta 2m) from the culture medium. M0Ab W6/32 cross-reacted with various H-2 class I antigens only in the presence of bovine or human beta 2m but not in the presence of beta 2m from other species (goat, sheep, rabbit) or syngeneic mouse beta 2m. The exposure of the W6/32 determinant on mouse cells was dependent on the concentration of human or bovine beta 2m and was influenced by the temperature and time of incubation. The reaction pattern of W6/32 on a large panel of mouse strains showed that the binding is due to at least two critical factors: (i) the H-2 haplotype of the target cells; and (ii) the substitution of murine beta 2m for bovine or human beta 2m. These results show that exposure of a polymorphic class I determinant is dependent on the species origin of beta 2m with which the heavy chain is complexed. Comparison of beta 2m amino acid sequences from various species does not give a clear answer about the shared quality of human and bovine beta 2m. One amino acid position (89) was identified at which human and bovine beta 2m are identical but differ from all other known beta 2m sequences.

Polymorphic and autoreactive H-2-specific monoclonal antibody isolated after injections of syngeneic sendai virus-coated lymphocytes

An H-2-specific monoclonal antibody (mAb Q-1) was obtained from B10.Q (H-2q) mice injected with syngeneic Sendai virus-coated cells. The IgM monoclonal antibody recognizes the public determinant H-2.25 shared by H-2k (Kk) and H-2r haplotypes and cross-reacts with H-2d, H-2s, H-2p, and H-2q cells, the latter being the haplotype of the challenged B-cell donor. The binding of mAb Q-1 to H-2d, H-2s, H-2q, and H-2p cells was lower than to H-2k and H-2r and of decreasing affinity but could be clearly distinguished from the negative reactions with H-2b and H-2f cells. MAb Q-1 distinguishes between Sendai virus-coated and uncoated lymphocytes only cells with low-affinity binding. On virus-coated or infected (H-2p, H-2q, H-2d, H-2s) cells lysis was stronger than on normal lymphocytes. We interpret the enhanced lysis of Sendai virus-positive cells by mAb Q-1 to be due to recognition of a modified exposure of public H-2 determinants induced by Sendai virus.

Immunization with syngeneic Sendai virus-infected cells induce no MHC-restricted antibodies but antibodies specific for H-2 class I determinants

To find out whether immunoglobulins are able to recognize foreign antigens in the context of syngeneic MHC determinants, an effort was made to trigger the production of MHC-restricted antibodies by syngeneic Sendai virus (SV)-infected cells using the spleen-fragment culture technique. Antibodies were found that mimicked MHC-restricted antibodies by recognizing MHC + SV better than MHC alone. However, the binding was not specific for SV and also occurred on mitogen-stimulated (SV−) or influenza virus-infected cells. We describe the production of H-2 class I-specific lymphocytotoxic antibodies by primary B cells responding to syngeneic SV-infected cells. No viral-specific, H-2-restricted antibodies were found.

Monoclonal H-2 Class I Specific Antibodies Isolated After Immunization of C57B1/6 Mice with Syngeneic Sendai Virus-Coated Cells

Two alloreactive H-2 (class I) specific cytotoxic IgM monoclonal antibodies (McAbs), B6-1 and B6-2, were isolated from C57B1/6 (B6) mice after injections of syngeneic Sendai virus-coated (SV+) spleen cells. McAb B6-I recognizes the public H-2 class I specificity H-2.25, shared by the H-2k(Kk) and H-2r haplotypes and cross-reacts with H-2z antigens on SV-infected (SVi) lymphoblasts. McAb B6-2 recognizes the private H-2Kf determinant H-2.26 on normal Sendai virus-negative (SV-) spleen cells but cross-reacts with H-2Kk and H-2Dd antigens on SVi blast cells. A polymorphic reaction pattern, that was dependent on the presence of Sendai virus, as tested on a panel of B10 target cells, was also observed with the cytotoxic immune sera from the mice whose cells were used in fusion experiments. Given the fact that each immune serum is an extensive mixture of anti-H-2 antibodies with different specificities, the isolated McAbs can be seen as illustrative examples which explain the reaction pattern of the immune sera. The recognition of polymorphic determinants on SV-infected, positive cells, is presumably due to a modified exposure of cross-reacting public H-2 class I determinants. Taken together, the lymphocytotoxic McAbs induced by injections of syngeneic SV+ cells recognize neither viral antigen nor self-MHC+X composite determinants, but allogeneic H-2 determinants as presented on normal, SV-coated or SV-infected cells.

Searching for MHC-Restricted Antibodies: Antibodies Induced by Injections with Syngeneic Cells Coated with Sendai Virus, Trinitrophenyl, and Xenogeneic β2-Microglobulin Are Not Restricted by the Mouse MHC

The capacity of the immune system to discriminate among an enormous number of different antigens is mediated by two distinct but interactive subpopulations of lymphocytes, B and T cells. These subpopulations differ profoundly in the way they recognize foreign antigens. B cells use immunoglobulins (lg) as cell surface receptors for recognition of free antigen whereas the lg-Iike receptors on T cells (TcR) recognize foreign antigens presented by their own major histocompatibility complex (MHC) gene products, a phenomenon known as MHC restriction (Zinkernagel and Doherty 1979). Another major difference exists between the structure and recognition of lg and the TcR. Immunoglobulins are composed of two heavy and light chain disulfide-Iinked hetrodimers while one set of disulfide-linked α- and β-glycoproteins forms the functional TcR (Kappler et al. 1983). The genomic organization of the genes for B (Tonegawa 1983; Honjo 1983) and T (Gascoigne et al. 1984; Hayday et al. 1985) cell receptors are similar and it is likely that the gene families originate from the same ancestral gene (Hood et al. 1985). Recently, it has been suggested that the T cell αβ receptor molecule has an antigen specific binding site that is fundamentally not different from the conventional binding site on antibodies (Novotny et al. 1986). The structural basis for the difference in the mode of antigen recognition between B and T cells might therefore be in the structure of the antigen that is recognized. Thus while the epitopes that occupy the binding sites of immunoglobulins are derived entirely from the antigen, the epitopes recognized by T cell receptors may be derived in part from the nominal antigen and in part from the restricting MHC molecule and can be seen as a neodeterminant.

Exposure of the W6/32-Defined Determinant on Mouse Cells Is Dependent on the Interaction of Certain H-2 Heavy Chains with Human or Bovine β 2 -Microglobulin

The HLA class I specific monoclonal antibody (McAb) W6/32 recognizes an antigenic determinant shared in humans by all products of the HLA-A, -B, and -C loci (Barnstable et al. 1978). The W6/32 determinant involves only amino acids of the HLA-A, B, C chain and is a product of their three-dimensional configuration stabilized by the association with β 2-microgobulin (β 2m) (Parham et al. 1979). This determinant has further been detected on the cells of some other primates and on bovine cells but not on cells from a number of other species, including mice (Brodsky et al. 1979, 1981; Brodsky and Parham 1982). It has, however, been reported that the W6/32 determinant is exposed on mouse cells expressing the H-2Db allele (Ivanyi and van der Meugheuvel 1984; Maziarz et al. 1986). Here we summarize the findings which show that the appearance of the W6/32 determinant on mouse cells results from the association of certain D or K gene products with either bovine or human β 2m.

MHC -Restricted Antibodies: Facts and Interpretation

T cell recognition of foreign antigen is MHC restricted. This restriction holds for helper as well as cytolytic T cells. A major part of the problem of MHC restriction is connected with the structure and binding site specificity of the T cell receptor (TcR). The serendipity of discovery and changing views about TcR specificity have been reviewed by various authors. The most typical situation can still be characterized by the original description of the MHC restriction phenomenon by Zinkernagel and Doherty (1974, 1979). They found that antiviral cytotoxic T-lymphocytes (CTLs) recognize antigen only on target cells together with self-MHC molecules. The phenomenon has been amply confirmed, although various observations have extended the horizon: (a) viral-specific CTLs frequently recognize MHC alloantigens without virus, (b) determinants shared by various MHC molecules can restrict antigen recognition (cross-reactions among MHC molecules), (c) determinants shared by various foreign antigens can be recognized by the same CTL (cross-reactions among foreign antigens), (d) allo-(MHC)-restricted clones are induced when responder cells are stimulated with alloantigen and virus, and (e) exceptionally, autoreactive T cell clones have been described that have recognized not only allogeneic but also syngeneic cells without antigen.