INHIBITORY EFFECT OF SALIVA FROM SECRETORS AND NONSECRETORS ON BINDING OF MENINGOCOCCI TO EPITHELIAL-CELLS

Carriage of Neisseria meningitidis B:4:P1.15 was higher among non-secr etors during a school outbreak of meningitis; non-secretors had lower levels of anti-meningococcal salivary IgM. Flow cytometry was used to assess effects of secretor and non-secretor saliva on binding of B:4:P 1.15 to buccal epithelial cells: (1) to assess inhibition by IgA and I gM; and (2) to assess contributions of salivary antibodies to inhibito ry activities. Greater inhibition was obtained with secretor saliva: p ooled (P = 0.049); fresh (P = 0.0001). Purified IgA (P = 0.02) and IgM (P = 0.03) were equally inhibitory. After absorption of anti-meningoc occal antibodies, there was still significant inhibitory activity in t he pools: secretors (P = 0.018); non-secretors (P = 0.005). These resu lts indicate that both secretory immunoglobulins and other factors con tribute to protection against colonisation by meningococci and might e xplain the increased carriage of B:4:P1.15 in this population.