Red blood cells, a source of factors which induce Neisseria gonorrhoeae to resistance to complement-mediated killing by human serum

Lysates of guinea pig or human red blood cells (RBC) contain far more of the factors that induce resistance in gonococci to complement-mediated killing by fresh human serum that do plasma or serum. As was previously found with serum, most of the resistance-inducing activity of guinea pig RBC lysates was found in ultrafiltrates with molecular weights of less than 5000. In contrast, and as with human serum, most of the resistance-inducing activity of human RBC lysates did not pass ultrafilters which removed molecules of less than 5000 daltons, although some active material of low molecular weight was present.