Abstract: Keratinocyte treated by psoriatic serum could form the cellular adhesion with human mononuclear leucocytes.The promoting adhesion ability of psoriatic serum was significantly higher than that of normal serum.When IgG,IgA,IgM in the sera were removed,promoting adhesion ability of the sera was practically cancelled.Pure psoriatic IgG possesscd promoting adhesion ability,but IgG-F(ab')₂,did not.It is suggested by these facts that the farmation of adhesion depends on the connection between Fc of antibody molecules Bound on the surfaces of keratinocytes and Fc receptors on mononuclear leucocytes.It was show by immunophenotyping that mono/macrophage,T_H,T_S and B cell participated the cellular adhesion.