Effect of preliminary incubation of human peripheral blood lymphocytes on intensity of transformation induced by phytohemagglutinin

Preliminary incubation of lymphocytes in a leukocyte suspension or isolated in a Verografin-Ficoll gradient at 37°C leads to more intensive blast transformation in response to stimulation by phytohemagglutinin (PHA). Preincubation in the presence of soy trypsin inhibitor (500 μg/ml) abolishes this effect. The results suggest that neutral proteinases of neutrophils or monocytes participate in modification of the response to PHA.