Immunology of leishmaniasis.

Knowledge of the immunological basis of the leishmaniases and of the host's response is fragmentary and largely pragmatic. This paper reviews certain conceptual and clinical aspects of the immunology of these diseases. Consideration is given to man's natural resistance and his ability to acquire resistance from natural infections and from vaccination. The age-distribution of infection in different populations is discussed in relation to the effects that interaction between the parasite and its intermediate host may have on its infection characteristics and virulence.Studies in the USSR of differences in virulence among 30 human strains and 39 rodent strains are reported. The rodent strains showed a broader range of virulence than did the human isolates. Serological tests for determining species relationships among the leishmaniae are generally nonspecific, but work concerned with the development of the antiserum-culture test is reviewed. Species identification and the recognition of new forms, perhaps with different infection characteristics, is, nevertheless, of the utmost importance in the prevention and treatment of the disease.The review concludes with a discussion of functional immunity and hypotheses of the immune process in leishmaniasis.