Effects of lymph node stromal cells on the differentiation of a cell line established from an atypical prolymphocytic leukemia with phenotypes of both chronic lymphocytic and hairy cell leukemias.

We investigated the effects of stromal cells, obtained from lymph nodes with various lymphoid disorders and characterized immunocytochemically as fibroblasts, on the maturation of a cell line "HN" established from an atypical PLL (prolymphocytic leukemia) having phenotypic characteristics of both CLL (chronic lymphocytic leukemia) and HCL (hairy cell leukemia). Coculture with stromal cells, irrespective of the kind of lymphoid disease affecting the lymph node, induced a plasmacytoid cytology in HN cells, an increase of cIg gamma, and decreases of sIg gamma, CD5, CD21, HC2, and B-ly7. In contrast, coculture with the stromal cells produced no marked effects on hairy cells from two HCL patients. Similarly, coculture with stromal cell supernatant or with various cytokines shown to be produced by bone marrow stromal cells produced no effects on HN cells. We propose that lymph node stromal cells play an important role in the differentiation of B cells through direct contact and that HN cells will be useful for investigating the differentiation pathway of chronic B cell leukemia cells.