Lymphokines. VI. Factors in human and other heterologous sera inhibiting the migration of guinea pig macrophages.

Different heterologous sera including human, rabbit, bovine and fetal calf serum (FCS) showed a strong inhibiting effect on the migration of guinea pig peritoneal macrophages (GPPM), compared to the migration of GPPM in homologous guinea pig serum. The inhibiting effect of these sera on the migration of horse monocytes on the other hand was much less marked. Fractionation of human and rabbit serum showed the 4 S fraction to be most inhibitory on GPPM migration. The migration inhibiting effect of heterologous sera on GPPM was prevented by addition of homologous (GP) serum, by absorption of the sera by various guinea pig cells, by heating at 56 degrees and by addition of alpha-L-fucose. Human sera were found to be strongly cytotoxic for 51Cr-labelled guinea pig erythrocytes and lymphocytes, but not for horse lymphocytes. Upon absorption with guinea pig erythrocytes, lymphocytes and kidney cells, the cytotoxicity of the human sera was strongly reduced. Accordingly, the role of heterophilic antibodies and/or of heat-labile MIF-like factors in heterologous sera has to be considered in al macrophage migration experiments where heterologous sera are being used. These factors may differ from the heat-stable MIF activity generated upon antigen- or mitogen-induced stimulation of cultured lymphocytes.