The enzyme histochemistry of lymphoid and non-lymphoid cells of the human palatine tonsil: a basis for the study of lymphomas.

The distribution of various hydrolytic enzymes has been determined in 27 human palatine tonsils by means of conventional enzyme histochemical techniques, and lysozyme (muramidase) activity has been localised in eight tonsils by the unlabelled antibody peroxidase-antiperoxidase complex (PAP) method. The enzyme activities of various cell types are compared and the effect of various methods of fixation and processing discussed. The results suggest that arrangement of various histiocytic cells types within the tonsillar follicles and crypt epithelium is related to the processing of antigen. The PAP method for lysozyme demonstrates a smaller population of cells than is demonstrated by the alpha-naphthyl acetate esterase (ANAE) method. T-cells are demonstrated by the presence of dot-like ANAE activity in their cytoplasm. Large numbers of the lymphocytes of this type were located in the T-dependent areas of the tonsil, and are frequent beneath the crypt epithelium. The efferent lymphatic vessels appeared to contain an almost pure population of T-cells. The immunohistochemical method for lysozyme did not differentiate between T- and B-cell areas, dot-like activity being absent. As in other workers' studies on non-lymphoid cells of the murine spleen, several types of glass-adherent cells have been identified in short-term cell cultures from the human tonsil. True dendritic cells and branching macrophages differ in several ways (as in the mouse spleen). The tonsil is considered to be a useful control "reactive" lymphoid organ, to act as a baseline tissue in an extended study of morphology and enzyme histochemistry in the lymphomas.