Abstract
Persistent hypocomplementemia is often recognized in patients with systemic lupus erythematosus (SLE) even in cases of a clinical remission. To elucidate the pathogenesis of persitent hypocomplementemia, we measured plasma C3a and C4a, catabolic products of C3 and C4, respectively, by radioimmunoassay.
Fifteen SLE patients were divided into three groups based on clinical activity and the presense of hypocomplementemia as follows, group I-inactive disease without hypocomplementemia, group II-inactive disease with hypocomplementemia, group III-active disease with hypocomplementemia. Nineteen healthy volunteers were also chosen as control.
Mean value of plasma C3a in group II was 699±200ng/ml, significantly higher than that of group I (p<0.01). Therefore it was suggested that the complement activation played an important role in persistant hypocomplementemia in inactive SLE patients.
Mean values of plasma C3a and C4a in group I were 254±158 and 377±75, compared with 89±58 and 207±69 in control group (p<0.05, p<0.01), suggesting that the potential complement activation was constantly present in SLE patients.
Mean values of plasma C3a and C4a in group III (918±79, 1, 728±730ng/ml) were markedly elevated, compared with those of group II (p<0.10, p<0.01), although there was no significant difference in the serum complement levels between these two groups.
We conclude that the measurement of plasma C3a and C4a may be very useful for themanagement of SLE patients.
