Phagocytosis and intracellular killing of mucoid and nonmucoid variants of Pseudomonas aeruginosa by polymorphonuclear leukocytes: effect of specific immune sera.

Nonmucoid variants (NM) of 6 Pseudomonas aeruginosa strains were better phagocytized and intracellulary killed by rabbit peripheral polymorphonuclear leukocytes (PMNs) than their mucoid variants (M). The ratios of ingested and killed bacteria of both variants significantly increased in the presence of immune serum with antibodies against slime and somatic antigen (anti-OM) in the phagocytic mixture. Immune sera prepared for slime layer only enhanced the both activities of PMNs against M variant. The anti-O sera significantly increased the phagocytosis and killing of NM variants belonging to the same serogroup of O antigen as the strain used for the preparation of immune serum.