Salivary immunoglobulins and antibody activities in leprosy.

The technics of immunodiffusion and the fluorescent leprosy antibody absorption (FLA-ABS) test were used to determine the levels of immunoglobulins and their antibody activities against Mycobacterium leprae in the serum and the saliva collected from a total of 110 patients with leprosy (50 lepromatous, 24 borderline, and 36 tuberculoid). The average levels of serum IgG, IgM, and IgA were not significantly different among these patients. In saliva, however, IgM was detected in only two cases with lepromatous leprosy and three tuberculoid cases. Salivary IgG and IgA levels and their ratios to those in the sera were not significantly different according to the classification of leprosy. The percentages of positive FLA-ABS tests in the sera and saliva were compared by using fluorescent antibodies specific for IgG, IgM, and IgA, respectively. The results indicated that M. leprae-specific antibodies in the serum were mainly found in IgG and IgM and, less frequently, in IgA. IgG antibodies were found more frequently in lepromatous and borderline patients than in tuberculoid cases. On the other hand, salivary IgA antibodies against M. leprae were found in a significant number of specimens; whereas IgG and IgM antibodies were scarcely found. However, the percentage of positive FLA-ABS tests caused by salivary IgA antibodies was higher in the patients with tuberculoid or borderline leprosy than in those with lepromatous leprosy. A significant number of patients with tuberculoid or borderline leprosy secreted M. leprae-specific IgA antibodies into saliva without detection of circulating IgA antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)