The isolation and establishment in vitro of a hitherto undescribed type of lymphocyte designated D.G.-75 is reported. The original inoculum was derived from the pleural effusion of a child with a primary abdominal lymphoma, which clinically and histologically resembled Burkitt's lymphoma. In addition to the absence of the EBV genome and EBV receptors, this line possesses a number of other properties which distinguish it from previously described lymphoblastoid cell lines. It has different growth characteristics and morphology; does not form EAC or E rosettes (representative of B and T) cell surface markers, respectively); possesses IgM-kappa immunoglobulins on the cell surface (B lymphocyte), has an unusually high cap-forming ability and low agglutinability with fluorescent concanavalin A. One homologue of the No.14 chromosome pair possesses extra chromatin material as revealed on chromosome banding. This abnormal chromosome marker is similar to that described in biopsies and cultured tumor cells from patients with African Burkitt's lymphoma.

Lymphocytes isolated from the peripheral blood and from tumor tissues of patients with African Burkitt's lymphoma have been studied for cap formation and agglutinability by Concanavalin A (Con A). Peripheral blood from healthy adult persons served as a normal control and blood from patients with carcinoma served as a non-lymphoma control. These studies included 29 patients with Burkitt's lymphoma, 93 with carcinoma, and 105 healthy adult persons, as well as tumor tissues from 13 patients with Burkitt's lymphoma. The great majority of the carcinomas were from the face and neck regions. Lymphocytes from the blood of the majority of patients with Burkitt's lymphoma, as well as those from tumor tissues, exhibited a reduced cap-forming ability (2-6%) and increased Con-A-induced agglutinability compared to lymphocytes from healthy normal donors and from patients with carcinoma, although some of the lymphocytes from patients with carcinoma had a somewhat lower range of cap formation than the lymphocytes from healthy donors. No difference was observed in the interaction with Con A of lymphocytes from the different types of carcinoma studied. Eight lymphoid cell lines were established in our laboratory from the tumor tissues of patients with Burkitt's lymphoma. The cap-forming ability and agglutinability by Con A of these lines was examined and compared to those of the "classical" lymphoma lines: Raji, Daudi and P3HR1. All cell lines exhibited an increased Con-A-induced agglutinability and a reduced cap-forming ability compared to normal lymphocytes, except for P3HR1 cells which exhibited a cap-forming ability of 15-20%. These findings are discussed in relation to the association of the lymphocytes with malignancy and as a possible aid in the differential diagnosis between malignant lymphomas and other diseases.

No abstract