Influence of levamisole on the immune response of old people.

Fifteen healthy people, over 70 years old, have been treated during 1 month with Levamisole at the dose of 150 mg a day, twice a week. They have been compared to 15 controls matched for age and sex. At the start of the study, each subject was injected with 0.2 ml of a diphtheria-tetanus vaccine. Levamisole had no effect on the following immune parameters known to be altered in old age: serum IgE concentration, specific IgE and IgG antibody response to diphtheria toxin, lymphocyte response to phytohemagglutinin (PHA). There was a slight and transitory effect of Levamisole on the isohemagglutinin titer. In vitro, Levamisole was weakly mitogenic for the peripheral blood lymphocytes from old and young control subjects but there was no influence on the response to PHA.