The detailed distribution of HLA-A, B, C antigens in normal human organs.

We have used a monoclonal antibody, PA2.6, directed against the heavy chain of HLA-ABC antigens to study the detailed tissue distribution of MHC class I antigens. Normal tissues from throughout the human body were obtained fresh from organ donors or operative specimens and were snap-frozen in liquid nitrogen within 1-2 hr of removal. Frozen sections were then studied using a sensitive peroxidase-antiperoxidase immunohistological technique. The results of our study show that class I antigens could be detected on most, but not all, the nucleated cells in the body. They were only weakly detectable in several tissues including endocrine cells in the thyroid, parathyroid, pituitary and islets of Langerhans in the pancreas and on gastric mucosa, the myocardium, skeletal muscle, and hepatocytes in some of the specimens. Spermatozoa were positively stained in the testis, but as they moved up into the epididymis class I antigens were no longer detectable. We found that class I antigens were not detectable on corneal endothelium, some Brunner's glands in the duodenum, villous trophoblast, central nervous system neurones, the exocrine portion of the pancreas, and acinar cells in the parotid. We conclude, therefore, that class I antigens are not ubiquitous, as previously thought.