Relation between anti-Mycobacterium leprae antibody activity and clinical features in borderline tuberculoid (BT) leprosy.

Antibody activity against Mycobacterium leprae antigen 7 was determined by radioimmunoassay and IgG antibodies against various antigens present in an M. leprae sonicate by a solid phase radioimmunoassay in 77 patients with borderline tuberculoid (BT) leprosy. In both assays there was a wide variation in antibody activity in individual patients although all were diagnosed as having BT leprosy. The median antibody activity was lower in newly diagnosed cases than in patients appearing with active skin lesions or new skin lesions despite dapsone (DDS) treatment of long duration. Further comparison of patients with high and low antibody activity revealed that high antibody activity was significantly correlated statistically with active skin lesions, new skin lesions and neuritis despite DDS treatment of long duration. The reason for variation in antibody activity in newly diagnosed BT leprosy remains unclear, and this patient group is of particular interest for further characterization of the basis for variation in antibody activity in tuberculoid leprosy.

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.