[Cytokines, immunoglobulins, and IgG subclasses in patients with IgG plasmacytomas]

Cytokines play an essential role in normal and malignant B-cell proliferation and isotype-switching. Therefore we determined serum levels of different B-cell activating cytokines including IFN gamma, IL-4 and IL-10, IgG subclasses, further immunoglobulins and the soluble B-cell activation marker sCD23 in 68 patients with recently diagnosed and previously untreated IgG myelomas in comparison with age- and sex-matched healthy controls. Our results demonstrated that 16% of the myeloma patients had elevated IL-10 levels up to 1000 pg/ml and 8% showed increased IFN gamma serum concentrations. By contrast, only 7% of the controls showed detectable IL-10 levels and 3% had measurable IFN gamma levels. While in men 67% of the paraproteins were of the kappa light chain type, we found an equal occurrence of kappa and lambda light chains in women. In addition, the distribution of IgG subclasses differed in men and women. In comparison with the controls, no alteration of sCD23 was detected in myeloma patients. We found an apparent correlation of elevated IL-10 levels and the IgG1 subclass.