Effect of treatment on antibody activity against Mycobacterium leprae antigen 7 in tuberculoid leprosy

Anti-Mycobacterium leprae antigen 7 antibody activity was determined by radioimmunoassay during treatment in a longtime study of individual patients with newly diagnosed borderline tuberculoid (BT) leprosy and in BT leprosy patients who were suspected from their case histories to have dapsone (DDS) resistant leprosy. There was a strong correlation between clinical and antibody activity, and clinical improvement following treatment led to a marked decrease in antibody activity in most cases. A characteristic pattern of rapid and marked increase in antibody activity shortly after the initiation of treatment was observed in patients with newly diagnosed BT leprosy. This pattern may become of practical importance in the evaluation of patients with BT leprosy as an indicator that the therapy is effective, even though this pattern was associated with a transient increase in inflammatory activity in the skin lesions. The association of inflammatory activity with increased antibody activity strongly indicates that the underlying processes are associated with the stimulation of both humoral and cellular immune responses.