Preliminary investigations on abnormal immunoglobulin(s) in leprosy.

A new, abnormal immunoglobulin designated IgK has been discovered in leprous Rubino-negative sera. The IgK having a negative net charge and its own antigenic specificity appears to be partly related to the Fc fragment of IgA and to Fab fragments of known immunoglobulins, but its net charge is negative at pH 8.8. Its molecule seems to possess kappa but not lambda light polypeptide chains. Implications of this discovery are discussed.

Bacteriological status (point prevalence) of lepromatous outpatients under sulfone treatment.

The study concerns 337 outpatients with lepromatous leprosy who had been receiving dapsone treatment for 1-26 years-69% of them regularly and 31% irregularly. Routine bacterial examination (10 min per slide) by a paramedical technician showed only 50% of these patients to be bacteriologically positive. This rate attained 99% when each slide was examined for 30-60 min by a qualified bacteriologist. Other factors-apart from the limited action of sulfones-might account for these unexpected results: the material was collected by an experienced leprologist; the disease was still clinically active in 75% of the patients; about 25% of them had been treated for only 1-4 years; and the intake of dapsone in long-term treatment gradually decreases.

Immunological determination of Mycobacterium leprae by means of cytoplasmic antigens.

Mycobacterium leprae was isolated and purified from lepromas, the spleen, and the liver of leprosy patients. An immunodiffusion analysis of the cytoplasms obtained from four lots of M. leprae and M. lepraemurium, 295 strains of different actinomycetales, and 12 other bacteria was performed with the use of the cytoplasm antisera. Immunological relationships were revealed between the cytoplasms of M. leprae, M. lepraemurium, M. avium, M. gallinarum, M. tuberculosis, M. simiae, M. kansasii, M. chitae, M. capsulatum, Actinomyces israelii, A. naeslundii, and some strains of saprophytic mycobacteria. These studies led to the proposed concept of the immunological evolution of M. leprae and M. lepraemurium and an Actinomyces-like progenitor through M. avium-M. gallinarum and to a proposal for the polyvalent vaccine currently being developed by this research group.

Serology in leprosy.

A critical survey of the literature on serology in leprosy has shown that sera taken from lepromatous patients display some striking differences in comparison with sera from tuberculoid patients. The tests most frequently employed were complement-fixation, haemagglutination, electrophoresis, precipitation and immunofluorescence, together with a variety of antigens not only from lepromas but also from Mycobacterium tuberculosis and other actinomycetales.With the exception of the Rubino test, all these serological tests are lacking in specificity for leprosy since leprous sera have a broad range of reactivity with different antigens, including those employed in the serological diagnosis of syphilis.Some features of the leprous sera could be related to a hypersensitivity state involving circulating immune complexes, low levels of complement and the presence of antibodies similar to those found in sera from patients with autoimmune diseases.