Class I and II major histocompatibility complex gene product expression by a rat insulinoma cell line in vitro following exposure to gamma interferon

A study of Class I and II major histocompatibility complex gene product expression by a rat insulinoma cell line (RINm5F) was performed using monoclonal antibodies and immunoperoxidase techniques. RINm5F cells were incubated with different concentrations of gamma interferon. RINm5F cells exhibit low levels of Class I molecules and are normally devoid of Class II gene products. Upon exposure to gamma interferon, RINm5F cells showed a dramatic increase in Class I expression. This expression was homogenous and could be detected on all cells after 18 h of incubation with as little as 1 unit/ml of interferon. In contrast, de novo Class II expression was not homogeneous and required 36 h of incubation with 10 units/ml of interferon. The number of RINm5F cells expressing Class II antigens was dose- and time-dependent. Interferon treatment did not affect the morphology of RINm5F cells as determined by ultrastructural analysis. Withdrawal of interferon from the culture medium for as long as 78 h diminished but did not abolish the expression of Class I and Class II molecules already induced. The ability of interferon to enhance expression of Class I gene products and induce de novo expression of Class II molecules on B-cell-derived RINm5F cells supports the hypothesis that aberrant expression of major histocompatibility complex gene products on pancreatic B cells may be an important factor in triggering the immune response in Type 1 (insulin dependent) diabetes mellitus.