Activation of the Alternative Pathway by Pneumococcal Cell Wall Teichoic Acid

Abstract

Abstract Previous studies on the interaction of pneumococci and the alternative pathway have shown that the cell wall, rather than the cell membrane or capsule, plays a major role in the activation of the alternative pathway. The present study was performed in order to identify the biochemical component of the pneumococcal cell wall responsible for activating the alternative pathway. Teichoic acids were extracted from purified pneumococcal cell walls by three different procedures (0.05 M periodate at 37°C; 100% formamide at 170°C; 5% TCA at 4°C). In each case the teichoic acids were able to consume C3 in C4-deficient guinea pig serum (C4D GPS) at concentrations as low as 3 to 10 µg/ml. In contrast, the residual cell walls, which contained the peptidoglycan, lost their activity in proportion to the amount of teichoic acid that had been extracted. Notably, cell walls extracted with periodate lost over 98% of their teichoic acid and the residual cell wall peptidoglycan was unable to consume C3 in C4D GPS at concentrations as high as 1 mg/ml.