FIG. 2.

Immune adherence of pneumococci to erythrocytes obtained from WT mouse, CR1⁺ mouse, or human erythrocytes. The bacteria were opsonized with WT mouse serum (A) or C3-deficient mouse serum (B), followed by incubation with WT mouse, CR1⁺ mouse, or human erythrocytes (E). (A) The immune adherence of pneumococci to either CR1⁺ mouse or human erythrocytes, assessed as the mean fluorescence (MF) of erythrocytes, was significantly higher than that to WT mouse erythrocytes (*, P < 0.01 by a Student's two-tailed t test). (B) The increased immune adherence exhibited with CR1⁺ mouse and human erythrocytes was C3 dependent. Error bars indicate the standard deviations (SD) of data from triplicate samples.