Expression of antigens of the carcinoembryonic antigen family on B cell lymphomas and Epstein-Barr virus immortalized B cell lines.

Abstract

Expression of antigens of the carcinoembryonic (CEA) family on B cell lymphomas and Epstein-Barr virus (EBV) immortalized B cell lines was studied using two CEA reactive mAbs. Results from experiments where five B cell lymphomas and two immortalized B cell lines, one from fetal liver and one from normal blood, were analyzed by flow cytometry, showed that all cell lines were strongly reactive with both mAbs. Glycoproteins of 66-90 kDa were identified in cell lysates and spent medium of metabolically labelled cells, immunoprecipitated with the two anti-CEA mAbs and analyzed by SDS-PAGE autoradiography. In cell lysates, a polyclonal anti-CEA antibody reacted with two molecules of 78 and 90 kDa. EBV negative lymphomas, converted, in vitro, with EBV, expressed significantly higher glycoprotein levels, as compared with the parent cell lines. Furthermore, two additional glycoproteins of 45 and 33 kDa were found in lysates from these cells. Northern analysis of mRNA from four of the lymphoma and one of the EBV immortalized B cell lines, using a probe which hybridizes with all CEA family members, showed two CEA related transcripts of 3.9 and 2.2 kb. Based on the sizes of the transcripts and of the glycoproteins, it was concluded that some of the CEA antigens expressed on B cells were, most likely, alternatively spliced forms of biliary glycoprotein.