Differences of the in vitro reactivity of lymphocytes from normal and persistently lymphocytotic cows to enzootic bovine leukosis tumour membrane extracts as detected with the macrophage-electrophoretic mobility test.

The response of peripheral blood lymphocytes from normal and persistently lymphocytotic cows to cell membranes and sodium cholate-extracted membrane proteins from normal and tumourous lymph nodes was tested with the macrophage-electrophoretic-mobility test with guinea pig peritoneal macrophages as indicator cells. Lymphocytes from 13 cows with persistent lymphocytosis (PL) showed a positive reaction with cholate extracts from tumour cell membranes. On the other hand, there was a negative reaction with corresponding extracts from normal lymph nodes for 11 animals. 4 of 10 hematologically normal cows also showed a positive reaction against tumour cell membrane extracts. One of these, however, thereafter developed antibodies against BLV glycoprotein gp 51. Using tumour cell membrane preparations as antigen, the 4 cows with PL tested also exhibited a positive reaction, whereas none of 3 hematologically normal cows showed any reactivity. As efforts to detect the main antigenic proteins of BLV (gp 51, p 24) in detergent extracts of tumour cell membranes proved unsuccessful, these findings are thought to provide evidence for the existence of a common non-viral antigen on cell membranes of bovine leukosis tumour cells.