Different responses elicited in vitro by antibodies to IgM and IgD in cells from a surface IgM + D-positive human follicular lymphoma

The effect of anti-Igs in combination with the tumour promotor TPA on DNA and Ig synthesis in a human follicular germinal centre cell lymphoma carrying sIgM and sIgD was investigated. The lymphoma cells responded to both anti-mu and anti-delta chains and to anti-lambda light chains by DNA synthesis, as measured by methyl-(3H)-thymidine incorporation. Flow cytofluorometric measurements, however, showed that only anti-mu chains induced marked increase in cytoplasmic Ig content. This result suggests that in certain B-cell subsets the signals elicited via sIgM and sIgD are different.