The effect of levamisole on cellular immunity in multiple sclerosis.

The lymphocyte stimulation test has been standardized in a normal human population using four virus cell-associated antigens (VCAA): human embryonic lung cells infected with the LEC and Norrby strains of measles virus, mumps virus, and vaccinia virus. Following 1 week of treatment with the immunopotentiating drug levamisole, a group of multiple sclerosis (MS) patients was found to have increased lymphocyte stimulation responses toward VCAA and increased delayed hypersensitivity responses towards a battery of skin test antigens. No change in the percentage of short- or long-incubation E rosettes occurred. Measles haemagglutinin inhibition (HI) antibody titres measured before and after the entire course of levamisole therapy (12 weeks) did not change. The neurological status of five out of seven MS patients deteriorated while they were taking levamisole.