Induction of human gamma interferons by a mitogen derived form Mycoplasma arthritidis and by Phytohemagglutinin: differential inhibition with monoclonal anti-HLA.DR antibodies.

Abstract

The peripheral blood lymphocytes from eight healthy volunteers produced significant amounts of interferon (IFN) when co-cultured with a recently discovered mitogen preparation derived from cultures of Mycoplasma arthritidis (MAS). Maximum levels of 281 to 2187 U were reached after 3 to 4 days of incubation. The IFN was characterized as IFN gamma on the basis of pH and heat lability, and neutralization with anti-human IFN gamma but not anti-IFN alpha. A monoclonal antibody to HLA.DR determinants suppressed IFN induction and lymphocyte proliferation when co-cultured with MAS but was not effective against PHA-induced IFN and proliferation; PHA-induced proliferation was enhanced in the presence of the antibody. Anti-HLA.DR-mediated inhibition of lymphocyte functions, however, was not specific for MAS inasmuch as viral-induced IFN was also suppressed, as was Con A-induced proliferation. These and other studies suggest that the cellular requirement for T cell activation by MAS, PHA, and Con A may all be distinct.