Effect of multiple sclerosis alpha 2-macroglobulin on mitogen induction of lymphocyte proliferation.

Electrophoretic studies on microheterogeneity of alpha 2-macroglobulin (alpha 2M) have revealed the presence of an abnormal acidic form of alpha 2M in multiple sclerosis (MS). In the present study we have characterized alpha 2M chemically and compared the inhibitory effect of MS and normal alpha 2M on the mitogen induction of lymphocyte proliferation. The antitrypsin activity and total reducing sugar content of MS alpha 2M were comparable with those of normal alpha 2M. However, the sialic acid content of MS alpha 2M was found to be significantly higher than that of normal alpha 2M. In agreement with previous studies, normal alpha 2M was found to inhibit the mitogen induction of lymphocyte proliferation in more than 90% cell cultures. However, MS alpha 2M was found to inhibit the mitogen-induced lymphocyte proliferation in less than 35 percent cell cultures. The effects of MS or normal alpha 2M on the lymphocyte cultures of either groups were found to be apparently the same. The possible explanations for the loss of the above-mentioned inhibitory effect of MS alpha 2M have been discussed.