FIG. 4.

Complement activation and C3 deposition onto pneumococci via the alternative pathway. PspA⁺ and PspA⁻ strains were incubated with 30% NMS from CBA/N mice in the presence of Ca²⁺ and Mg²⁺ or in the presence of EGTA (blocking the activation of the classical/MBL pathway) and Mg²⁺. The result of a representative experiment of three is shown.