PRECIPITATING ANTIBODY IN HUMAN SERUM TO AN ANTIGEN PRESENT IN CULTURED BURKITT'S LYMPHOMA CELLS

Burkitt's lymphomal has been the object of intense interest in recent years, particularly in view of epidemiological evidence suggesting that it may be caused by a virus.2 Herpes simplex virus,3' 4 reovirus," 6 and unidentified infectious agents7 have been isolated from the tissues of patients with Burkitt's lymphoma, but it is not known that any of them is etiologically related to the disease. Burkitt's lymphoma cells were established in continuous cultures first by Epstein and Barr8 and by Pulvertaft,9 and more recently by Stewart et al.,'0 Rabson et al.," and Osunkoya.12 Epstein, Achong, and Barrl3 observed particles resembling herpes virus in cultured Burkitt's lymphoma cells; similar particles have been seen by Stewart et al.'0 and Rabson et al." in the lines they established. In an extensive study, Epstein et al.'4 found no evidence of infectivity in preparations containing these particles. Stewart et al.," however, described a transmissible encephalitis in hamsters which was originally initiated by inoculating cultured lymphoma cells or extracts of these cells into thymectomized hamsters. These culture lines have been used to detect antibody in human serum by immunofluorescence tests on fixed cells'6 and by complement-fixation tests.'7 Positive reactions were observed in high frequency with the sera of patients with Burkitt's lymphoma and with sera from adult residents of the United States. The two tests did not give uniformly parallel results and so may be detecting different antigens. Using fresh Burkitt's lymphoma cells obtained by biopsy, Klein et al.'8 observed positive reactions in the indirect immunofluorescence test on viable cells with sera of patients with Burkitt's lymphoma, including in some instances the serum of the patient whose cells were used for the test. Positive reactions were observed also with sera from African patients with other diseases and infrequently with sera from healthy relatives of patients with Burkitt's lymphoma. We have examined approximately 400 sera from African and American donors for cytotoxic antibodies reactive with cultured Burkitt's lymphoma cells'9 by the same methods that led to the demonstration and description of several leukemia-specific antigens in the mouse (see review20). Positive reactions were found, but on further analysis these were attributed to isoantibodies or to naturally occurring antibody against a cell-attached component of the calf serum in which the cells were grown, the latter reactions disappearing when the cells were cultured in human serum. The purpose of this communication is to report the occurrence in human sera of precipitating antibody that reacts with antigen prepared from a culture line of Burkitt's lymphoma cells (Jiyoye).