Flagellar antibody stimulated opsonophagocytosis of Pseudomonas aeruginosa associated with response to either a- or b-type flagellar antigen

Pseudomonas aeruginosa exhibit one of two flagella types: a homogeneous b type, with molecular weight of 53,000, or a heterogeneous a type (subtypes a0, a1, a2, a3, and a4), with molecular weights ranging from 45,000 to 52,000. Pseudomonas aeruginosa flagellar antiserum was shown to promote uptake of radiolabeled bacteria by mouse polymorphonuclear leukocytes. Bacteria were detected directly associated with washed leukocytes and visualized, by electron microscopy, internalized in polymorphonuclear leukocytes. Phagocytosis was specific for the flagella type (a or b) in that homologous flagella serum enhanced uptake three to four times greater than heterologous serum or normal rabbit serum. An a-type antiserum was shown to enhance phagocytosis of four different a-type strains with varying subantigen types, indicating the presence of a common cross-reactive a0 antigen in this flagella type. Phagocytic killing of internalized bacteria was not seen with the addition of only flagellar antiserum.