Leucocyte antigens in human post mortem tissues: their preservation and loss as demonstrated by monoclonal antibody immunohistological staining.

The development of monoclonal antibodies and of techniques for demonstrating antigens in situ in frozen tissue sections has been responsible for remarkable progress in diagnostic histopathology. We explored the potential of these techniques when applied to post mortem tissues that were frozen at various intervals after death and stained by monoclonal antibodies using immunoperoxidase technique. The monoclonal antibodies were selected according to their reactivity with essential markers of the lymphatic system and also to their availability. Lymph nodes and splenic tissue from 30 autopsy cases were stained in addition to thymic tissue from eight deceased infants. The antigens proved to be surprisingly well preserved. Staining could be precisely evaluated with UCHT1, OKT6 and anti-Leu-7 antibodies at least 72 h after death; staining with DAKO-pan-B, DAKO-LC and anti-Leu-3a was also very reliable. Antigens expressed by T-suppressor lymphocytes and dendritic reticulum cells were less well preserved. The T8-antigen of suppressor lymphocytes was usually demonstrable in the lymph nodes but less frequently in the splenic tissues. It is concluded that most leucocyte antigens are very resistant to post mortem disintegration, and that they can be reliably interpreted by immunohistological staining using monoclonal antibodies. We therefore recommend this in autopsy specimens in cases where in-vivo examination was not feasible.