Studies on gonococcus infection. V. Observations on in vitro interactions of gonococci and human neutrophils

The association of in vitro human leukocytes with pilated, type 2 Neisseria gonorrhoeae exceeds that for nonpilated, type 4 organisms but is less than that for nonpilated, type 4(*) gonococci. The two nonpilated forms of gonococci (types 4 and 4(*)) attach to tissue culture cells to a much lesser extent than do pilated, type 2 organisms of the same strain. Trypsin treatment of either pilated (type 2) or nonpilated (type 4(*)) gonococci markedly reduces the attachment-ingestion of these organisms with leukocytes, but the same trypsin treatment does not depilate the type 2 organisms nor visibly alter the morphology of their pili. Similar reductions in association with leukocytes are found if the gonococci are pretreated with chymotrypsin, heat, or glutaraldehyde. High levels of association between gonococci and leukocytes are reestablished if the trypsin or chymotrypsin-treated organisms are reincubated in protease-free medium. These data suggest that interactions between gonococci and human neutrophils are mediated through surface characteristics of the bacteria, different from those which influence attachment of the organisms to tissue culture cells. In the latter instance, pili appear to positively influence gonococcal attachment, whereas in the former a nonpilus bacterial cell wall nonpilus protein is probably the major determiner in the interaction between leukocytes and gonococci.