Distribution of Forssman antigen in chickens.

The distribution of Forssman antigen in various tissues of chickens was studied by the indirect and direct immunofluorescence (IF) tests using rabbit immune serum against purified Forssman glycosphingolipid (GSL) [GalNAc (alpha, 1-3)GalNAc(beta, 1-3)Gal(alpha, 1-4)Gal(beta, 1-4)Glc-ceramide]. A general finding in all tissue sections was the presence of Forssman antigen in vascular endothelium and perivascular connective tissues. Erythrocytes gave a Forssman positive reaction, but the intensity of fluorescence was slight. Forssman antigen was found in about 20% of all peripheral leukocytes. Fractionation of lymphocytes from peripheral blood into T and B lymphocytes showed that about 30% of the B lymphocytes gave a positive reaction, while only 2-3% of the T lymphocytes gave a positive reaction. About 40% of bone marrow cells expressed Forssman antigens. On the other hand, about 40-50% of adherent cells in vitro cultures from spleen were Forssman-positive. The antigen was also abundant in hematopoietic organs, such as spleen, thymus and the bursa of Fabricius. Positive reactions in the digestive tract, ovary, testis and skin varied from portion to portion of the tissues. In brain and spinal cord, only the vascular endothelium gave a positive reaction. In peripheral nerves, only the connective tissue stroma around the nerve fibers gave a positive reaction. In other tissues, the distribution of the antigen was generally in accord with the results of Tanaka and Leduc (1956). These positive reactions in the IF test were specifically inhibited by addition of purified Forssman GSL. The distributions of Forssman antigen in tissues were found to be the same in chickens of various ages.