Responses of chronic lymphocytic leukemic lymphocytes to increasing concentrations of phytohemagglutinin during short-term culture.

Lymphocytes obtained from CLL patients containing high and low peripheral lymphocyte cell counts were cultured in the absence and presence of increasing concentrations of phytohemagglutinin for periods of up to 2 h. Lymphocytes from patients with low cell counts (less than 50,000/mm3) were stimulated to incorporate 3H-uridine during the 1st h of culture by concentrations of PHA ranging from 1 to 32 microgram/ml. Under identical conditions, lymphocytes from patients with high cell count (greater than 50,000/mm3) were barely affected. During the 2nd h of culture the above concentrations stimulated to a lesser degree the former group of lymphocytes, whereas it inhibited incorporation by the latter group. The results obtained suggest a qualitative difference in the response of CLL lymphocytes to PHA in accordance with the progression of the disease.