Pattern of expression of tetraspanin antigen genes in Burkitt lymphoma cell lines
Tetraspanin antigens are implicated in the prognosis of different types of tumours. In this study we determine by semiquantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) the level of 13 tetraspan messages in 21 Burkitt lymphoma (BL) cell lines. All tumour cell lines have a common pattern of tetraspanin gene expression. There are five antigens which are detected in 90% of cell lines at high levels, CD53, CD81, CD63, SAS and CD82. Another two, CD9 and CD37, were detected in 60% of cell lines, and have a very variable level of expression. The remaining antigens, A15, CoO29, KRAG, L6, TI‐1 and il‐TMP, are expressed at low levels in very few cell lines without any specific pattern. The level of gene expression corresponds with the level of cell surface antigen determined by flow cytometry. The average number of tetraspan proteins expressed per cell line is six. These proteins may form subunits of an oligomeric structure with 24 transmembrane domains. There are no major differences in tetraspan expression pattern among sporadic or endemic tumours, type of translocation or Epstein–Barr virus status, suggesting the original cell of these tumours is the same, probably a late pre‐B cell, at the CD9 to CD37 transition point. Tetraspanin gene expression is consistent with BL being a single entity, despite variations in other parameters.