ANTILYMPHOCYTE SERUM IN THERAPY AND PREVENTION OF ACUTE SECONDARY DISEASE IN MICE

The capacity of antilymphocyte serum (ALS) to suppress acute secondary disease was ascertained in lethally irradiated mice grafted with allogcneic spleen cells. Suppression of the acute graft-versushost reaction was measured in terms of survival and freedom from that disease’s symptoms either when ALS was injected directly into experimental animals or when the spleen cells were incubated with various concentrations of ALS prior to grafting. Injection with 0.25 ml of ALS (10-12.5 ml/kg) on the 4th day after irradiation and grafting was of moderate value in preventing acute secondary disease. Severe subacutc secondary disease was evident in all survivors. Incubation of spleen cells with ALS was of limited value in suppressing the severe secondary disease response. Survival and incidence and severity of subacute secondary disease in the survivors were of variable proportions. Limited testing with ALS was done with mice devoid of a demonstrable intestinal microflora. Survival in these animals, as compared to that in conventional mice, was increased either as a consequence of direct injection with ALS or when the spleen cells were exposed in vitro with ALS prior to grafting. The survival data are discussed in terms of the nonspecific action of ALS and the influence that microorganisms have in irradiated animals grafted with lymphoid cells and treated with immunosuppressive agents. © 1969 by The Williams and Wilkins Co.