In vitro cytokine, sCD23 and IgG secretion in multiple sclerosis

Synthesis of IgG by peripheral blood mononuclear cells from patients with multiple sclerosis (MS) and with other neurological diseases and from healthy controls was induced by Pokeweed mitogen (PWM) in short-term cultures. As expected, MS patients produced more immunoglobulin (Ig) G and had a higher percentage of 'high responders' to PWM stimulation as compared to controls. Interleukin (IL)-4 was undetectable in all samples. IL-6 and tumor necrosis factor (TNF)-alpha synthesis was induced by PWM stimulation in all groups, but MS patients showed the most significant increase of both cytokines. Interestingly, only MS patients showed a significant increase of the soluble form of CD23 receptor (sCD23). Moreover, only sCD23 levels correlated with in vitro IgG production in MS patients. The levels of IL-6, TNF-alpha, sCD23 were greater in high responders compared to low responders in all groups. The mean value of each molecule, however, did not differ significantly among overall groups. A highly significant difference was reported for sCD23 in MS patients. We suggest that sCD23, also known as B cell growth factor, may play a role in the well-documented phenomenon of in vitro IgG hypersynthesis in MS patients, adding support to the concept of B cell up-regulation in the peripheral blood of these patients.