In vitro studies on dermal granulomas of human leprosy--cellular characteristics.

Single-cell suspensions from the granulomas of leprosy cases were prepared for an in vitro study of the properties of the infiltrating cells. Biopsies from 44 untreated patients with tuberculoid and lepromatous leprosy were analyzed. The granulomas were found to contain lymphocytes and "large cells" (epithelioid cells and macrophages). The number of lymphocytes was significantly higher in the suspensions from the tuberculoid granulomas in comparison to the suspensions from the lepromatous granulomas. A high percentage of lymphocytes from the tuberculoid granulomas formed rosettes with sheep erythrocytes, and also showed the presence of esterase as dots in the cytoplasm. However, the lymphocytes did not form rosettes with EAC. Most of the "large cells" from both types of granulomas were esterase positive, exhibited peroxidase activity, and did not carry receptors for C3. A high percentage of "large cells" in the tuberculoid granulomas was nonadherent to a plastic surface, while the lepromatous granulomas contained a high proportion of adherent "large cells."