A buffy coat stimulating effect in serum from cattle with persistent lymphocytosis.

A stimulating effect on bovine buffy coat cells was demonstrated in blood samples from cattle with persistent lymphocytosis. The stimulation was a function of the serum and not the cells used. It was not altered by filtration or inactivation of the serum. When buffy coat cells were grown in homologous serum, the resulting growth was moderate to abundant when the donor animal had persistent lymphocytosis and was usually poor when the donor animal had a consistently normal hemogram.