Free immunoglobulin light chain synthesis by neoplastic cells in leukaemic reticuloendotheliosis

Neoplastic cell preparations from four patients with clinically and morphologically well-defined leukaemic reticuloendotheliosis (LRE) were investigated for their capacity to synthesize immunoglobulin in vitro. Neoplastic cells from all cases synthesized immunoglobulin of the same light chain class as expressed at their cell surface. Labelled IgM and IgD were identified in cell lysates while free light chain was the predominant labelled immunoglobulin product in the LRE culture supernatants. The capacity of LRE cells to synthesize immunoglobulin and free light chain was similar to that of neoplastic cells from patients with chronic lymphocytic leukaemia, and provides further evidence for the B-lymphocyte origin of the neoplastic cells in LRE.