Mimicry of the a determinant of hepatitis B surface antigen by an antiidiotypic antibody. I. Evaluation in hepatitis B surface antigen responder and nonresponder strains.

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Abstract
B and T cell responses of several strains of mice, immunized with a monoclonal antiidiotype (anti-Id) that mimics the a determinant of hepatitis B surface antigen (HBsAg), were studied to determine if the immune response to the anti-Id was regulated by H-2-linked immune response genes as has been previously observed for HBsAg. We report that immunization with anti-Id could elicit HBsAg-specific antibodies in mice of the H-2d,q, or f haplotype and in an outbred wild mouse strain (Mus spretus), thus circumventing the H-2 haplotype restriction pattern observed when immunizing with HBsAg in H-2f mice. Purified lymph node T cells from mice of the H-2d or q haplotype and M. spretus that were primed in vivo with HBsAg or anti-Id could be stimulated in vitro with either HBsAg or anti-Id but not with an irrelevant antibody of the same subclass as the anti-Id. However, purified lymph node T cells from H-2f mice that were primed in vivo with the anti-Id could only be stimulated in vitro with anti-Id. No in vitro stimulation whatsoever was observed in H-2f mice immunized with HBsAg. The effect of processing and presentation of the anti-Id by antigen-presenting cells (APC) was studied in mice of the H-2d haplotype. Stimulation of purified lymph node T cells by HBsAg and anti-Id was shown to be strictly dependent on APC and restricted by major histocompatibility complex class II antigens at the I-A locus. Treatment of APC with paraformaldehyde or chloroquine abrogated the T cell response to all antigens except for a nine-amino acid synthetic peptide representing a partial analogue of the group a determinant of HBsAg S(139-147). The significance of these results is discussed in the context of understanding the mechanism of mimicry elicited by the anti-Id.