Phagocytosis of live versus heat-killed bacteria by human polymorphonuclear leukocytes

Heat-killed Pseudomonas aeruginosa are phagocytized much more slowly by human polymorphonuclear leukocytes than are the live organisms. The post-phagocytic increase in hexose monophosphate shunt activity (HMS) parallels the ingestion of the bacteria. The addition of serum to the live organisms causes a marked increase in both ingestion and cellular HMS activity; serum actually causes an inhibition of both uptake and HMS activity when added to the heat-killed organisms. Differences in postphagocytic HMS activity between live and heat-killed organisms were observed with three different species of bacteria, indicating that the phenomenon is not restricted to P. aeruginosa. These data emphasize that the influence of the particle on the phagocytic process is considerable.