Inhibition of human monocyte spreading. An in vitro test for immunosuppressive potency of antihum lymphocyte globulin.

Monocytes from human peripheral blood, when incubated in vitro, spread onto the surface of the glass. Horse antihuman lymphocyte globulin (ALG) added to the incubation chamber inhibits the spreading, while normal horse globulin (NHG) does not. The inhibition depends on the concentration of ALG admixed to the mononuclear blood cells. Eleven coded samples of antihuman ALG were assayed for the ability to inhibit monocyte spreading. This potential was then compared to the in vivo immunosuppressive effect of the same samples determined by the prolongation of skin allograft survival in subhuman primates. It was found that the in vitro inhibitory acttivity correlated rather well with the in vivo immunosuppression, Therefore, the inhibition of monocyte spreading is proposed as an additional test system for the in vitro evaluation of the immunosuppressive potential of antihuman ALG.