Evaluation of humoral immunity on leprosy patients in Taiwan: a preliminary report.

Twenty-four tuberculoid (T)-type and 31 lepromatous (L)-type leprosy patients from Taiwan Provincial Lo-Sheng Leprosarium were enrolled in this study. Twenty-six age- and sex- matched normal subjects were also studied as a control group. The evaluation of their general and specific humoral immunity included B-cell subpopulations, 3 major classes of immunoglobulin (G, A and M) and antibodies in the IgG class against lepromin suspension and Bacillus Calmette-Guerin (BCG) sonicate. T-type patients showed a larger B-cell percentage than L-type patients (p less than 0.01). In general, patients with leprosy, both T and L types, had higher serum immunoglobulin levels than the control group. T-type patients showed greater antibody levels than the control group (p less than 0.05 for anti-lepromin and p less than 0.0001 for anti-BCG). L-type patients demonstrated a higher anti-BCG IgG level than the control group (p less than 0.0001). The level of anti-BCG IgG was more frequently above the cutoff level than that of anti-lepromin IgG in leprosy patients (p less than 0.01 for T, p less than 0.005 for L). In conclusion, humoral immunity is not impaired in leprosy patients. Discrepancies for T- and L-type patients among B-cell subpopulation, serum immunoglobulin levels and specific antibody levels reflect different aspects of cell-mediated immunity impairment. Though leprosy patients had elevated anti-BCG IgG levels, it is impossible to differentiate L- and T-type patients; specific antigens are needed for serodiagnosis of leprosy patients in Taiwan.