Antinuclear factors in murine alloantisera.

We have demonstrated that anti-Thy 1.1 and certain of H-2 alloantisera contain an antinuclear factor (ANF) detected by fluorescent antimouse IgG. The incidence of ANF positive antisera that we report may actually be an underestimate. ANF is present in sera not only from our laboratory but also from other sources; thus ANF is not an artifact of our laboratory. ANF is not identical to alloantibody, and the ANF appears to be of an autoimmune nature. A variety of environmental and genetic factors may influence the appearance of ANF in anti-H-2 sera, but we believe that the consistent detection of ANF in sera directed against H-2.31,34 or against H-2.4 suggest that some specific aspect of immune stimulation by these H-2 antigens, and likely by other H-2 antigenic specifications, induces the appearance of ANF. It is not known whether it is these K and D antigens or other determinants associated with the H-2 complex that may actually provide the immune stimulation for ANF induction. The particular mechanisms that may be operating to induce ANF cannot be determined at present. We are continuing with experiments to define what parameters influence the appearance of ANF in alloantisera.