Effect of growth in serum on uptake of neisseria gonorrhoeae by human neutrophils

Because serum exposure precedes interaction of invasive Neisseria gonorrhoeae with neutrophils, neutrophil association with gonococci grown in serum was assessed. Uptake of a nonpiliated serum-resistant strain grown in 20% serum was reduced to 63.5% of control values. Heated serum (20%) yielded similar results. Stimulation of hexose monophosphate shunt activity in neutrophils by heated serum-grown gonococci (a phenomenon reflecting phagocytosis) was 64.5% of control values. Because gonococcal outer membrane (OM) structures mediate interaction with neutrophils, lithium acetate-treated OM preparations of gonococci grown in heated serum were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Multiple new protein bands and a quantitative decrease in amounts of proteins I, II, and III were noted. However, a decrease in the amounts of these membrane proteins was not observed with alternative membrane extraction techniques. Gonococcal growth in 20% serum dialyzed in 3, 500-molecular-weight exclusion tubing allowed normal neutrophil association and OM protein expression.