A line of Burkitt lymphoma cells derived from a patient in Kenya, Africa, has been established in vitro. This cell line, designated B35M, consists of primitive lymphoblasts, and is similar to all lines of Burkitt lymphoma cells established previously by others. The doubling time of B35M cells in suspension culture is approximately 21 hours. The cells continuously synthesize human immunoglobulins. B35M cells harbor virus-like particles that are indistinguishable by electron microscopy from those found in other lines of Burkitt lymphoma cells but attempts to identify the particles in B35M cells have been unsuccessful. The exact relationship of these particles to the host Burkitt lymphoma cells is as yet undetermined. EVERAL LINES OF BURKITT LYMPHOMA CELLS S established in vitrol, 5-69 carry morphologically identical virus-like particles.2, 5 , 7,138 1% 19, 21
T h e exact nature of the particles has not been established, but it seems likely that they may have some etiological significance in Burkitt's lymphoma, especially since they are found in cell lines developed in different laboratories processing different biopsy material by different techniques. T h e present paper deals with the establishment of a line of Burkitt lymphoma cells derived from a patient in Kenya, Africa, and describes certain characteristics of the line. A detailed description of the virus-like particles associated with this line has been prepared for publication elsewhere.22