Serological and immunochemical analysis of H-2 class I molecules encoded by the Db region

Antigenic determinants shared between HLA-A, -B, -C antigens and H-2 class I molecules modified by bovine beta-2 microglobulin

The specificity of the mouse class I-specific antibody COB6-3 was examined in detail. It was found to react with the mouse class I molecules H-2Db, Kd, and Qa-2, and with human HLA-A, -B, -C antigens. The specificity pattern of COB6-3, despite its different origin, was similar to that of the monomorphic HLA class I-specific antibody W6/32. Cross-inhibition studies show that on human cells the antigenic determinants recognized by the two antibodies are situated close together and may be identical. On mouse cells, reactivity of both antibodies was generated upon replacement of mouse beta-2 microglobulin (B2m) with its bovine counterpart, but differences in specificity were observed using human B2m.

Induction of H-2-specific antibodies by injections of syngeneic Sendai virus-coated cells

The capacity of the B cell immunoglobulin receptor to recognize complexes of Sendai viral and H-2b antigens was investigated by studying the antibody response to injections of syngeneic Sendai virus-coated (SV+) spleen cells in C57BL/6 (B6) mice. Almost all mice produced alloreactive anti-H2 lymphocytotoxic antibodies. In contrast, such antibodies were found very exceptionally in mice injected with normal (SV-) cells or with Sendai virus (SV) only. The reaction pattern of the cytotoxic antibodies induced was variable and ranged from almost anti-private to widely cross-reactive serotypes. The results of reactions on H-2-congenic, -recombinant and -mutant mouse strains, and of capping and immunoprecipitation experiments showed that the cytotoxic antibodies were directed against H-2 class I molecules. The anti-H-2 antibodies exhibited enhanced binding for SV+ target cells, but absorption experiments showed that this was not the result of cross-reactions with cell surface Sendai viral determinants or with a molecular complex of H-2 plus SV. This conclusion was supported by the observation that syngeneic SV+ cells were not the predominant targets for the induced lymphocytotoxic antibodies. Our results do not support the existence of MHC-restricted antiviral antibodies, but show the induction of anti-class I H-2 alloantibodies by injections with syngeneic SV-coated cells. We present a model for regular induction of anti-H-2 antibodies without intentional alloimmunization.

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.

Anti-MHC immunity detected prior to intentional alloimmunization. IV. Natural monoclonal H-2-specific antibodies

Naturally occurring H-2-specific antibodies can be detected rather frequently in sera of non-alloimmunized mice by sufficiently sensitive techniques (Cerny-Provaznik et al., 1985a; Cerny-Provaznik & Ivanyi, 1985). In this report, we summarize our experiences with the preparation of monoclonal anit-H-2 antibodies obtained from hybridization experiments from non-alloimmunized mice. From a total of 30 spleen cell hybridization experiments, we could isolate only four anti-H-2 monoclonal antibodies (mAB). Two of the mAB are described in this report. Monoclonal antibody By-2 is anti-Kf and mAB By-3 is anti-Db, Ds. We investigated which conditions favour the isolation of monoclonal H-2-specific antibodies from non-alloimmunized mice. The presence of naturally occurring serum antibodies, the age of the spleen donor mouse or non-specific B cell stimulation were not critical for the isolation of natural anti-H-2 mAB. We hypothesise that the 'natural' H-2-specific antibodies represent compartments of the B cell repertoire which were triggered by modified or aberrant self-MHC expression.