Immunologic researches in leprosy. Diagnostic applications.

Immunofluorescence and fluorescent microscopy permit the demonstration of fixation of antibody, previously made fluorescent, on a specific antigen. A direct technic reveals the antigen to which globulins representing the antibodies of immune serum, previously conjugated with a fluorescent substance, are fixed. An indirect technic makes use of antihuman globulins developed in rabbit sera and made fluorescent. The globulin antibodies, fixed on the homologous antigen, are made visible by this technic. The second technic is more widely used, as it demonstrates antibody fixation on any specific antigen without requiring previous conjugation of globulins with fluorescent material for each specific serum. It is of course significant to take essential precautions to avoid nonspecific fixation of excess Buorescent material on the proteins of the specific antigen. In 1963 we (.) were able to detect the presence of antileprosy antibodies in human leprosy sera, using leprosy bacilli obtained from nasal mucosa smears in lepromatous cases. The smears were fixed for ten minutes in cold acetone and then left for 30 minute~ in contact with the serum studied, After an antibody present in leprosy serum has been conjugated with fluorescein isothiocyanate (direct technic) it can be fixed to the bacilli and becomes visible by fluorescent microscopy. After contact for 30 min~tes with the serum studied and rinsing In physiologic saline, the smears are covere? for 30 minutes with a drop of rabbit antiserum containing antihuman globulin previously made fluorescent, and the an-