Changes of serum complement and of circulating immune complexes in patients with multiple sclerosis.

The changes of total hemolytic complement (CH50), of C3 and C1q components and of the circulating immune complexes (CIC) were studied in a group of 112 patients with multiple sclerosis (MS) and in 50 controls. The attack was taken as a basis of observation. It was observed that in MS attacks CH50, C3 and C1q were decreased owing to the activation of the complement in the classical way. The CH50 values were found well enough correlated with C3 and C1q (r = 0.535) and respectively r = 0.497) and clearly correlated with the CIC values (r = 0.907). A sharp decrease of CH50 increases the probability of the appearance of an attack with slow remission and the probability of an attack with slow remission is the greater, the greater the increase of CIC values. Low CH50, C3 and C1q values correlated with high CIC values may be considered markers of severity in MS.