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)