Defective CD3 mediated proliferation and LPS responsiveness in multiple sclerosis

Increased B cell and cytotoxic NK cell proportions and increased T cell responsiveness in blood of natalizumab-treated multiple sclerosis patients

Background

Changes in the blood lymphocyte composition probably both mediate and reflect the effects of natalizumab treatment in multiple sclerosis, with implications for treatment benefits and risks.

Methods

A broad panel of markers for lymphocyte populations, including states of activation and co-stimulation, as well as functional T cell responses to recall antigens and mitogens, were assessed by flow cytometry in 40 patients with relapsing multiple sclerosis before and after one-year natalizumab treatment.

Results

Absolute numbers of all major lymphocyte populations increased after treatment, most markedly for NK and B cells. The fraction of both memory and presumed regulatory B cell subsets increased, as did CD3^-CD56^dim cytotoxic NK cells, whereas CD3^-CD56^bright regulatory NK cells decreased. The increase in cell numbers was further associated with a restored T cell responsiveness to recall antigens and mitogens in functional assays.

Conclusions

Our data confirms that natalizumab treatment increases the number of lymphocytes in blood, likely mirroring the expression of VLA-4 being highest on NK and B cells. This finding supports reduction of lymphocyte extravasation as a main mode of action, although the differential effects on subpopulation composition suggests that cell-signalling may also be affected. The systemic increase in T cell responsiveness reflects the increase in numbers, and while augmenting anti-infectious responses systemically, localized responses may become correspondingly decreased.

Decreased CD3-mediated interferon-gamma production in relapsing-remitting multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system that has been postulated to be T-cell mediated. We examined the proliferation and cytokine secretion of mononuclear cells after stimulation with OKT3 (anti-CD3) monoclonal antibody concanavalin A, or ionomycin plus myristic acid palmityl ester in subjects with stable relapsing-remitting MS. Control subjects demonstrated good proliferation to anti-CD3 monoclonal antibody whereas subjects with relapsing-remitting MS showed a significantly decreased anti-CD3 monoclonal antibody-mediated response. There was no difference in concanavalin or ionomycin plus myristic acid palmityl ester stimulation between control subjects and MS subjects. Secretion of interferon-gamma was significantly decreased and transforming growth factor-beta was significantly increased from cultures stimulated with anti-CD3 monoclonal antibody, but not ionomycin plus myristic acid palmityl ester or concanavalin A, in MS patients compared to control subjects. Secretion of interleukin-10 and tumor necrosis factor-alpha was not different between control subjects and MS patients following stimulation with anti-CD3 monoclonal antibody, concanavalin A, or ionomycin plus myristic acid palmityl ester, or of interleukin-2 and interleukin-4 following stimulation with anti-CD3 monoclonal antibody or concanavalin A. An abnormality of signal transduction and secretion of the immunomodulatory molecule interferon-gamma may exist in MS via the CD3 T-cell receptor complex.