Human C7 polymorphism: Quantitative analysis of different phenotypes

Abstract

SummaryC7 polymorphism was investigated in a Japanese population (Tokyo). The C7 protein concentrations and hemolytic C7 activities in the serum samples of various phenotypes were measured by radial immunodiffusion (RID) and radial diffusion hemolysis (RDH). The mean C7 protein levels for the common phenotypes C7 1, C7 2-1, C7 3-1, and C7 4-1 were 88~, 103~, 63~, and 94~ of a standard, while the mean C7 activity levels were 96~, 90~, 63~, and 74~, respectively. Both the protein and the activity levels for C7 3-1 were significantly lower than those determined for the most common phenotype C7 1. The mean levels in two individuals of C7 3 phenotype were only 34~ in protein concentration and 47~ in functional activity. Concerning the ratio of functional to immunochemical C7 (i.e. the relative specific activity), there was no difference between the phenotypes C7 1 and C7 3-1. On the other hand, the mean hemolytic activity and the relative specific activity for C7 4-1 were significantly lower than those for C7 1.

A novel protein polymorphism of human complement C7 detected by a monoclonal antibody

“…The frequencies of C7 M and C7 N in both groups were significantly (X 2 test) different from those found in C7 1 homozygotes (p<0.1 each) and different from each other (p < 0.05). However, since one C7 3 subject was heterozygous C7 MN and eight C7 3-1 individuals were homozygous C7 M (Table 2), C7"3 is not always associated with C7*N. This, however, cannot be excluded for C7"2 or C7"4 and C7*M. The allelic association between C7*N and C7"3 might be of importance, since the latter is known to be a hypomorphic C7 variant (Hobart et al 1978;Washio et al 1988). …”