Dose-response curve for C3bc and TCC formation in NHS (n = 5), C2-deficient serum (C2 defS), or factor B-depleted serum (B depS) incubated for 1 h at 37°C with BCG bacilli. Note that C3bc values must be multiplied by 10. The values for PBS controls in NHS, in C2-deficient serum, and in B-depleted serum were 154, 132, and 245 AU of C3bc/ml and 16.0, 8.9, and 9.0 AU of TCC/ml, respectively. The data represent means of two experiments in triplicate.