Changes in cell surface antigen expression on human articular chondrocytes induced by gamma-interferon. Induction of Ia antigens.

Ia antigens (class II HLA molecules) have been detected on cells eluted from affected human cartilage in certain disease states, but not on normal cartilage cells. Because the presence of Ia antigens on chondrocytes may play an important role in rheumatic diseases, we investigated the induction of these molecules by gamma-interferon (gamma-IFN), a potent Ia-inducing lymphokine. Human articular chondrocytes were incubated with recombinant gamma-IFN, and the expression of Ia antigens was studied by cell sorter analysis, using a panel of reagents that detect monomorphic and polymorphic specificities of the DR and DQ Ia antigen families. While the induction of DR antigens, including polymorphic DR specificities, was readily obtained with gamma-IFN (50-95% positive cells), DQ antigens were negative or were displayed only on a lower percentage of chondrocytes (5-60%). In addition, incubation with gamma-IFN led to an increased expression of HLA class I antigens. The expression of various other surface markers either remained unchanged (as in 4F2 and BA-2) or showed tendencies toward decreased percentages (as in 83c2) or increased percentages (as in M phi R-17). No apparent change in cell morphology or growth pattern was observed.