Increased growth of viruses in lymphocytes treated with heterologous antilymphocyte serum

Heterologous antilymphocyte serum (ALS) was found to enhance significantly the growth of canine distemper virus in cultures of dog lymphocytes. Virus titres in the ALS-treated cultures were up to 80 times higher than in the control cultures. At least 12 hr of exposure to ALS were necessary before the cells could support increased virus growth. The increases in virus growth in the ALS-treated cultures were directly related to the number of lymphoblasts present in the culturc. The various factors contributing to the preferential growth of virus in the lymphoblasts were considered. These findings also suggest that the lymphoblasts produced by ALS therapy in vivo might similarly support enhanced rates of virus growth and thus predispose the host to the risk of severe virus infection.