Immunologic aspects of leprosy with special reference to the study of immunoglobulin E

The serum levels of IgG, IgM, IgD and IgE have been determined in normal subjects, individuals suffering from ascariasis and filariasis, and in leprosy patients. Allergic and parasitic diseases were excluded in these normal subjects and in leprosy patients before they were taken for the study of their serum IgE. The circulating IgG was significantly raised in both tuberculoid and lepromatous forms of leprosy and also in filariasis; IgM was significantly elevated in only the lepromatous form of leprosy, ascariasis as well as in filariasis; while IgA was exclusively raised in both forms of leprosy. IgD was detected in the sera of more subjects with ascariasis and filariasis than in normal individuals and leprosy patients. The mean level of serum IgE in 35 normal Indian subjects was 1,025 I.U. per ml, 9 of them (25%) having serum IgE concentrations above 700 I.U. per ml. The highest mean level of serum IgE was found in ascariasis (7,328 I.U. per ml), followed by leprosy (5,180 I.U. per ml), and filariasis (4,244 I.U. per ml). Furthermore, no significant difference between the mean serum IgE levels of tuberculoid and lepromatous leprosy patients was observed. Although the rise of serum IgE level in these parasitic diseases, as well as in leprosy, was spectacular, the augmented synthesis of this unique class of immunoglobulins was not invariably present in all patients. The results have been discussed on the basis of recent ideas on immunoglobulin synthesis.