Antibodies in Human Sera to Soluble and Viral Antigens Found in Burkitt Lymphoma and Other Lymphoblastoid Cell Lines2

Human sera were examined for antibody to complement-fixing (CF) antigens derived from lymphobiastoid cell lines. Two CF antigens were used: a soluble cell extract (S) antigen, nonsedimentable at 100,000 × g for 2 hours, and a partially purified Epstein-Barr (EB) virus particle (V) antigen. The results of CF tests were compared with those of an indirect immunofluorescence (IF) test using fixed EB3 Burkitt lymphoma cells. Screening (at 1:10 dilution) of 177 sera indicated that, in 128 sera positive by the IF test, 106 reacted in the CF test with V antigen and 72 with the S antigen. Virtually all sera reactive with the S angiten also reacted with the V antigen. Forty-nine sera negative in the IF test were also negative when examined for CF-S and CF-V antibodies. Titration of positive sera by the 3 tests revealed a high correlation between the IF and CF-V antibody titer. On the other hand, many CF-S antibody-negative sera had high IF and CF-V antibody titers. The reactivity of human sera in the 3 tests suggests that the antigens detectable by the IF and CF-V tests are closely related, while the S antigen is immunologically distinct. In EB virus-containing cells, no correlation existed between the concentration of S antigen and virus particles or percent of IF-positive cells. The S antigen was also detected in preparations derived from AMC30 cells, free of detectable EB virions, but not in preparations of KB, HeLa, or human embryonic lung cells.