FIGURE 8.

Effect of GAPDH on complement activation. A, in vitro activation of the C1 complex (0.25 μm) in the presence of human or pneumococcal GAPDHs. C1 activation was monitored by Western blot analysis as described under “Experimental Procedures.” B, C1q, C3b, and C4b deposition measured in the presence of normal human serum using anti-C1q, anti-C3, and anti-C4 antibodies on wild-type R6 and D39, R6 HBt, and D39 HBt strains (partially deficient for surface GAPDH). Results are expressed relative to the signal obtained with the wild-type R6 or D39 strains, respectively. The data shown represent the mean value ±S.D. of four (R6) or two (D39) independent experiments. Each experiment was done in triplicate. *, significance was determined by one-way analysis of variance; probability, p ≤ 0.05. Error bars correspond to S.D.