Use of cDNA Probes for Typing Cells of B Lymphoid Lineage: Application of Early Response Genes to the Analysis of Mature B Cell Malignancies.

In vitro phorbol ester-induced plasmacytoid differentiation of primary B chronic lymphocytic leukaemia (BCLL) cells is accompanied by the rapid, transient increased expression of a large number of early response genes (ERGs) whose expression is highly cell type specific. We have examined phorbol ester-responsive expression of a panel of 13 ERGs in a series of B cell lines representing different stages of differentiation and in primary malignant cells from patients with hairy cell leukaemia and with centroblastic-centrocytic non-Hodgkin's lymphoma. The results revealed a spectrum of ERG expression which appeared to be correlated with stage of differentiation relative to BCLL cells, where no two cell types gave an identical ERG response. These results, while preliminary, suggest that panels of ERG probes provide a useful approach for analysis of cell type which may help in mapping stages of differentiation arrest and defining cell lineage relationships amongst mature B cell malignancies.