Brief Definitive Report PARALLEL SYNTHESIS OF IMMUNOGLOBULINS AND J CHAIN IN POKEWEED MITOGEN-STIMULATED NORMAL CELLS AND IN LYMPHOBLASTOID CELL LINES* BY JIRI MESTECKY,

In sera and in secretions, J chains are found linked to molecules of polymeric IgA and IgM by disulfide bonds. Their function remains undetermined; the init ial concept that they were essential to the process of polymerization has been questioned. It is of special interest that J-chain synthesis is not restricted to cells producing polymeric immunoglobulins of the IgA and IgM classes; it has been detected in murine plasma cells that produce IgG as well as in those that synthesize only L chains (1-4). Within such cells, J chain was thought to be either linked to a small portion of intracellular immunoglobulin or in an unbound form, but it was not secreted except in assocmtion with polymeric immunoglobulins. In sections of human lymphoid tissues, J chain was found in the majority of cells that contained immunoglobulins (5).