Immunopathology of oral leukoplakia.

The lymphocyte transformation test was performed with autologous saline homogenates of leukoplakia. A negative correlation was established (P<0.05) between the (14)C thymidine uptake of lymphocytes in vitro and the non-pyroninophilic mononuclear cell infiltration in biopsies. A depression of lymphocyte transformation was revealed in patients with carcinoma or carcinoma in situ and some with epithelial atypia, as compared with those showing only hyperkeratosis and to a less extent those with acanthosis. A corresponding depression was not found when lymphocytes were stimulated with phytohaemagglutinin, Candida albicans or Herpes simplex antigens. The Pyroninophilic cell count was raised in biopsies with carcinoma or carcinoma in situ and in some with epithelial atypia or acanthosis. These result suggest that in leukoplakia the carcinomatous transformation may be associated with some immunological changes.