Inhibition of attachment of Neisseria gonorrhoeae to tissue cells by goat milk antigonococcal immunoglobulin G.

An immunoglobulin G (IgG)-containing fraction was isolated from milk, obtained from a goat before and after instillation of the mammary gland with Neisseria gonorrhoeae colony type 1 (T1). The presence of IgG and the absence of immunoglobulins-A and -M in this fraction was confirmed by immunodiffusion in gel and immunoelectrophoresis. Postinstillation IgG inhibited the attachment of the homologous strain of N. gonorrhoeae (T1) to tissue cells. The percentage of Rhesus monkey kidney cells with gonococci attached was 38.9% +/- 6.4. Inhibition was significant (P less than 0.01) when compared to the inhibitory effect of preinstillation IgG (73.5% +/- 3.1) or buffer control )76.8% +/- 2.8). Absorption of postinstillation IgG with rabbit anti-goat IgG or whole cell gonococci removed the inhibitory effect. Postinstillation IgG gave little or no inhibition of attachment (maximun 13%) of seven heterologous (T1) strains of N. gonorrhoeae to tissue cells. These results may provide a reason for recurrent gonococcal infection in humans despite the presence of circulating antibody (IgG) to N. gonorrhoeae. Such an antibody, if present in secretions bathing the mucosa, may fail to prevent infection and colonization of the urogenital tract by a different immunotype of N. Gonorrhoeae.