This study illustrates the consequences of smallpox revaccination in 45 lepromatous, 28 tuberculoid, and 47 normal individuals. Results obtained with intradermal inoculations indicated that the patients with leprosy were associated with a relative anergy against the vaccinia virus, the anergy being minimal in the tuberculoid leprosy but marked in the cases with lepromatous leprosy. Major vaccinial reactions were observed more often in patients with lepromatous leprosy than in the controls or patients with tuberculoid leprosy. Furthermore in a patient with lepromatous leprosy, vaccinia necrosum also developed. The smallpox vaccination with live virus also appeared as a provocative factor for the precipitation of lepra reaction in the lepromatous leprosy cases. After 3 weeks of vaccination, the frequency of the specific humoral antibody response was the same in the tuberculoid patients and controls while it was higher in the cases with lepromatous leprosy. The prevaccination titer of total hemagglutination inhibition antibody was significantly higher in the lepromatous leprosy cases. However, the postvaccinial, humoral antibody response of the lepromatous patients was of the same magnitude as that observed in the normal individuals, and it was mainly due to a 2-mercaptoethanol-resistant antibody.

About 1,200 million viable lymphocytes from normal but lepromin- and tuberculin-positive human beings were transfused in four patients of lepromatous and one of tuberculoid leprosy three times at monthly intervals. Three patients of lepromatous leprosy suffered from erythema modosum, whereas the other two developed severe reaction whenever put on the smallest dose of dapsone. In one patient of lepromatous leprosy, minimal improvement or none was observed, whereas in the remaining three cases of lepromatous and one of tuberculoid leprosy, clinical, bacteriological, as well as histological improvement occurred. Two of the five patients started to tolerate the dapsone during the period of study. The present study indicates that immunotherapy might have a definite role in the management of the disease especially in cases with erythema nodosum. Lawrence factor, prepared from leucocytes of normal donors, was transfused three times into four lepromatous leprosy patients who were intolerant to anti-leprosy drugs. The donors were healthy but were tuberculin and lepromin (Mitsuda) positive. The clinical, histological, bacteriological (morphological index), and immunological assessments of the patients were performed before and 5 months after starting the immunotherapy. In two patients conversion of Mitsuda reaction occurred, but there was no appreciable improvement in the clinical, histologic, and bacteriologic status of these patients.

An attempt was made to repair cell-mediated immunity in 7 patients suffering from lepromatous leprosy and severe erythema nodosum leprosum by intravenous infusion of 400 million allogeneic blood lymphocytes on 3 occasions. The lymphocytes were obtained from lepromin and tuberculin-positive subjects and were inactivated in vitro by treatment with mitomycin C. Immunotherapy with inactivated lymphocytes only modified the severity of erythema nodosum leprosum, without altering other aspects of the disease.