Normal functional capacity of blood lymphocytes in multiple sclerosis measured by stimulation with mitogens.

The effect of phytohemagglutinin (PHA) and pokeweed mitogen (PWM) on blood lymphocytes was studied in multiple sclerosis, patients with acute CNS infections, and healthy controls. No significant differences in lymphocyte proliferation were registered between the group of MS patients and the two other groups, irrespective of mitogen used. The ratio between the PWM and PHA responses did not differ significantly from the ratios in the two other groups. The lymphocyte proliferation with PWM was significantly lower in the group with acute CNS infections compared with controls. The results indicate that alterations in cell-mediated immunity, if present in MS, are not confined to lymphocytes outside the CNS.