Complement-fixing antigens in lymphoid cell lines of American origin.

Lymphoid cell lines from Americans with infectious mononucleosis (Choate, EH IV, and OP), and from a normal American (Cassio), were tested for presence of herpes-like virus by electron microscopy (EM) and immunofluorescence (IF), and for complement-fixing (CF) antigens, using both American and African sera. Whereas earlier tests of seven African (Burkitt) lymphoma cell lines showed an absolute correlation between presence of herpes-like virus and CF reactivity with either African or American sera, the same was not true of the American cell lines. Herpes-like particles were found in the Cassio line by both EM and IF, and in a few cells of the OP line by IF, but not by EM. The virus was not found in the Choate or EH IV lines by either EM or IF. African sera from either normal individuals or patients with Burkitt lymphoma contained CF antibodies to extracts of Cassio and OP cells. Normal American sera contained CF antibodies to these extracts as well as to extracts of Choate cells. The EH IV cell line did not produce CF antigens detectable with either African or American sera. The data indicate that the CF antigens of the herpes virus-negative Choate cell line were serologically distinct from those in Burkitt lines. However, it is possible that the antigens from both sources are related to the presence of the genome of the herpes-like virus.