Effect of dapsone (DDS) on T-cells and their response to PHA and lepromin in tuberculoid leprosy patients.

T and B cell counts and their response to PHA and lepromin were studied in 46 patients of polar tuberculoid leprosy (TT), divided into two age and sex matched groups. Twenty five normal healthy controls were similarly investigated. While one group consisted of 26 untreated TT patients, the other included 20 individuals who had taken dapsone, 50 mg daily, for 12 to 14 months. There was significant decrease in the number of T-lymphocytes and their response to PHA and lepromin was lower in the treated, as compared to the untreated patients and normal persons. No significant change was found in the number of B-lymphocytes in any of the groups.