A study of apoptosis in the human palatine tonsil.

Apoptosis is a morphological involution caused by a cellular suicide program which is associated with programmed cell death. Several reports have shown that Fas antigen mediated apoptosis and death of immunocytes in lymphoid tissues are induced through apoptotic mechanisms. The present study was designed to investigate apoptotic cells in human palatine tonsils by using in situ end-labeling (ISEL) technique and flow cytometric analysis with anti-Fas antibody. The ISEL technique showed that a number of apoptotic cells were present in the subepithelial area of the tonsil. Flow cytometric analysis showed that the number of anti-Fas positive cells in the tonsil was larger in adults than in children. Further, tonsillar lymphocytes were examined for mRNA expression of the Fas antigen using reverse transcription polymerase chain reaction (RT-PCR) method. Fas mRNA expression was confirmed in tonsillar lymphocytes. The results suggest that apoptosis may be related to morphological and immunologic involutions of the tonsil.