Abstract
38‐13 is a hybridoma‐produced monoclonal rat IgM which appears to define a Burkitt's lymphoma‐associated antigen (BLA). In this paper, we describe the reactivity of 38‐13 with a panel of human haematopoietic and lymphoid cell lines. In indirect immunofluorescence (IF) assays, 15 of 26 Burkitt's lymphoma (BL) lines studied were clearly stained with 38‐13 (from 13 to 100% positive cells) by microscope, with varying numbers of heavily labelled cells. In these positive cell lines, fluorescence‐activated cell‐sorter (FACS) analysis demonstrated that BLA was actually present on all the cells. Positive BL included Epstein‐Barr virus (EBV) genome‐carrying lines and EBV‐negative ones; thus, BLA is not related to the presence of EBV. Most of the 15 BL cells that reacted with 38‐13 contained a typical t(8;14) translocation, but had variant translocations such as t(2;8) and t(8;22). The cells were derived from BL patients of different geographical origins and clinical features. Four BL lines were poorly stained and seven were negative with 38‐13 in IF assays. The 32 EBV‐positive lymphoblastoid cell‐lines (LCL) studied were negative. In three line pairs, consisting of a tumor line and an LCL from the same patient, only the BL line was demonstrated to react with 38‐13. A series of non‐BL cells, including haematopoietic, lymphoid and solid tumor lines, all failed to react with 38‐13. Various attempts to modulate the expression of BLA on BL cells were unsuccessful. However, it cannot be ruled out that BLA is actually a transient B‐cell differentiation marker.