Contribution of humoral and cellular factors to the resistance to experimental infection by Pseudomonas aeruginosa in mice. I. Interaction between immunoglobulins, heat-labile serum factors, and phagocytic cells in the killing of bacteria.

Techniques have been described for the purification of mouse polymorphonuclear leukocytes (PMN) and macrophages and for determining their bactericidal activity against Pseudomonas aeruginosa in a rotating suspension. Requirements for human anti-Pseudomonas opsonins and heat-labile mouse serum factors have been determined. In the macrophage system, although heat-labile mouse serum factors had enhancing properties, both immunoglobulin G (IgG) and immunoglobulin M (IgM) opsonins alone sufficed to induce bactericidal activity. In contrast, both opsonins and heat-labile mouse serum factors were required for bactericidal activity by the mouse PMN. In the absence of heat-labile mouse serum factors, IgG and IgM opsonins contributed to the bactericidal activity of mouse macrophages to the same extent. However, in the presence of these factors, much less IgG than IgM antibody was required to achieve maximum bactericidal activity by these cells. Similarly, IgG opsonins were found to be more efficient than IgM opsonins in enhancing the killing of P. aeruginosa by mouse PMN.