Phytohaemagglutinin-induced lymphocyte transformation in leprosy.

Blood lymphocytes from Malay, Indian and Chinese patients with leprosy, and from race-matched controls, were cultured in the presence of phytohaemagglutinin. Cells from Malays and Indians with lepromatous leprosy and from Malays with tuberculoid leprosy transformed as well as cells from normal controls when cultured in normal (reference) serum. Cells from lepromatous Malays and Indians transformed significantly less well than cells from normal controls when cultured in autologous serum. Normal lymphocytes transformed significantly less well when cultured in serum from lepromatous or tuberculoid Malays or from lepromatous Indians than when cultured in serum from normal controls. Lymphocytes from lepromatous Chinese transformed significantly more extensively than those from normal Chinese, whether cultured in normal (reference) or autologous serum. The ratio of transformation in autologous serum to transformation in reference serum was significantly depressed for lepromatous Chinese. Although lepromatous Chinese serum, compared with normal Chinese serum, did not depress the response of lymphocytes from one donor, there was evidence of depression when cells from another donor were used. Cells and sera from Chinese patients biopsied for suspected nasopharyngeal carcinoma behaved similarly to those from lepromatous Chinese, and not to those of normal Chinese, whether or not nasopharyngeal carcinoma was found. Lymphocytes from patients with disease classified as stable, regardless of other criteria, transformed significantly less well in either normal or autologous serum than did cells from patients with downgrading (rapidly progressive) disease. This was true of all races. In the case of Malays and Indians with stable disease the cells also transformed less well than normal cells in reference serum. The difficulties in design, execution and interpretation of studies of lymphocyte transformation in disease and the importance of humoral factors are emphasized.