Production of a B cell growth-promoting activity, (DL)BCGF, from a cloned T cell line and its assay on the BCL1 B cell tumor.

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Abstract
Culture supernatants from a long-term alloreactive [mouse] T cell line, the Dennert line C.C3.11.75 (DL) contain a B cell-growth-promoting activity. This activity, termed (DL) BCGF, can be assayed on normal B cells or on the in vivo BCL1 tumor line. This activity can be distinguished from the T cell-replacing factor activity earlier found in DL supernates [(DL)TRF], which is required together with IL2 [interleukin 2] for the B cell plaque-forming cell response to erythrocyte antigens. The (DL)BCGF can be absorbed on untreated or glutaraldehyde-fixed BCL1. This absorption does not remove (DL)TRF activity. The production of (DL)BCGF is greatly enhanced when DL is cultured with IL2-containing supernatants. Sublines or clones of DL (DL.B10 and DL.A4) were obtained that make large amounts of (DL)BCGF in the absence of any stimulator cells or IL2.B cells from the Xid-deficient male (DBA/2 .times. CBA/N)F1 mice do not repsond to (DL)BCGF.