INTERLEUKIN-13 GENE-EXPRESSION BY MALIGNANT AND EBV-TRANSFORMED HUMANB-LYMPHOCYTES

Expression of the IL-13 gene in malignant tissues from 26 human B-cell lymphoid malignancies was analyzed by reverse transcriptase-polymeras e chain reaction (RT-PCR). A positive signal was detected in 16 cases, which included high grade B lymphomas, follicular lymphomas and B-cel l chronic lymphocytic leukemias, IL-13 mRNA was also detected in the 9 malignant B cell lines and in the 6 lymphoblastoid cell lines tested, as well as in freshly isolated malignant B cells from 2 patients with a Burkitt's lymphoma, Two of 8 T-cell lymphomas and 2 of 4 T-cell lin es expressed the IL-13 gene, In contrast, IL-13 gene expression was no t detected in any of the 5 non-lymphoid cell fines tested. No specific binding of radiolabeled IL-13 was detected on B cell lines, suggestin g an absence of IL-13 receptors on such cells. This conclusion was als o supported by the inability of IL-13 or anti-IL-13 antibodies to affe ct the growth of malignant B cells, Taken together, these results show that both malignant and EBV-transformed B lymphocytes, either freshly isolated or maintained as cell lines, express the IL-13 gene, This ra ises the question of the role of B lymphocyte-derived IL-13, a B lymph ocyte stimulating cytokine, on the in vivo function of normal B lympho cytes as well as on the in vivo behaviour of B lymphoid malignancies,