Mitogenic activity of influenza virus and haemagglutinin

Abstract

Influenza A viruses behave as T cell-independent B cell mitogens in vitro. The magnitude of the proliferation induced varies with the haemagglutinin subtype of the virus, the order being H2 > H1 for Balb/c mice. H3 viruses are equally mitogenic for all strains of mice tested. In contrast, the mitogenic response to H2 and H6 viruses is controlled by the I-E subregion of the major histocompatibility complex. These viruses are mitogenic only for strains of mice that express surface I-E antigen (haplotypes a, d, k, p, r), and not for haplotypes b, f, q, s, which fail to synthesize a normal Eα chain and do not express surface I-E antigen. Mitogenesis by H2 and H6 viruses may involve direct interaction of virus with I-E molecules on the B lymphocyte or on an accessory cell, whereas mitogenesis by H3 viruses does not appear to involve I-E. © 1985.