Human B cell lines express the interferon gamma gene.

Interferon gamma (IFN-gamma) production has been attributed exclusively to activated T cells and NK cells. We sought to determine whether human B cells express IFN-gamma. We studied 28 B cell lines including Epstein-Barr virus (EBV)+ normal lymphoblastoid B cell lines (N = 7), EBV+ B cell lines derived from patients with Burkitt's lymphoma with (N = 6) or without AIDS (N = 8), as well as seven EBV- B cell lines. All cell lines were studied by reverse transcription-polymerase chain reaction (RT-PCR). We detected constitutive expression of IFN-gamma in every B cell line. The tumor promoters PMA and teleocidin appeared to enhance this IFN-gamma expression in nearly every B cell line. The 517 bp amplicons spanning the entire protein coding region of the IFN-gamma mRNA from three representative lines were sequenced, definitively establishing that B cell IFN-gamma is identical to IFN-gamma from activated T cells and is not altered by derivation of the B cell lines from AIDS patients or by EBV status. Detection of IFN-gamma in the entire panel of EBV+ and EBV- cell lines suggests that the IFN-gamma gene is broadly expressed by human B cells. Our data imply that human B cells can be activated to produce IFN-gamma, further enmeshing B cells in the dynamics of immunoregulation.