Reduced mitogenic responses in cultures of lymphocytes from newly calved cows.

The proliferative responses to stimulation with phytohaemagglutinin (PHA) in cultures of lymphocytes from newly calved and non-pregnant cattle were compared. Lymphocyte cultures from newly calved cows were seen to respond less to PHA than cultures from the non-pregnant cows. It is suggested that this depression in responsiveness of lymphocytes in the immediate post-parturient period may be involved in the etiology of disease in cattle during the immediate post-parturient period.