I-E/I-C region-associated induction of murine gamma interferon by a haplotype-restricted polyclonal T-cell mitogen derived from Mycoplasma arthritidis.

Cell-free supernatants from cultures of Mycoplasma arthritidis induced significant levels of interferon when cocultured with murine splenic cells. On the basis of physicochemical characteristics and antibody neutralization studies, the antiviral substance was identified as gamma interferon. Use of inbred and congenic mouse strains established that splenic cells from mice expressing the H2k and H2d haplotypes produced interferon in response to M. arthritidis culture supernatants, but those from mice with H2b and H2q haplotypes did not. Further studies with recombinant mouse strains established that interferon induction by the mycoplasma supernatant was associated with the haplotype expressed at the I-E/I-C subregion of the murine major histocompatibility complex. The specificity seen for interferon induction was identical with that reported earlier for induction of cytotoxic lymphocytes and for lymphocyte proliferation in response to the mitogen. All of these reactions appear to be dependent upon binding of the mitogen to specific I-E/I-C region-coded products present on splenic cell surfaces. The observations presented introduce the concept that microbial mitogens or their lymphokine products might modify immune responses and defense mechanisms of the naive host in a genetically restricted manner.