Species-dependent regulation of monocyte/macrophage Ia antigen expression and antigen presentation by prostaglandin E.

The expression of Ia antigen by various murine and human macrophage populations and the ability of prostaglandins of the E series to regulate Ia antigen expression were explored. Monocytes and macrophages from human and murine populations demonstrated a dichotomy in the expression of Ia antigen. Both human monocytes and macrophages expressed elevated levels of Ia antigen compared to their murine counterpart. Murine macrophages appear to express elevated levels of Ia antigen only when actively interacting with T lymphocytes in vivo or with lymphokines in vitro. Prostaglandins of the E series can suppress murine macrophage Ia antigen expression, but have little effect on the expression of Ia antigen by human monocytes and macrophages. Also, prostaglandins of the E series do not modulate the ability of human monocytes to present antigen to autologous lymphocytes when studied over a broad concentration range. These data suggest that prostaglandin E compounds do not profoundly affect human monocyte/macrophage Ia antigen expression or human monocyte antigen presenting activity.