Antibody responses of monkeys to oral and local immunization with Streptococcus mutans

Monkeys were immunized with Streptococcus mutans by a number of routes in an attempt to elicit exclusively a secretory immunoglobulin A (IgA) response. Antibody responses were detected by a sensitive radioimmunoassay. Monkeys primed subcutaneously and boosted submucosally with formolized cells of S. mutans had high serum IgG, IgA, and IgM radioimmunoassay titers and only slight salivary IgG titers. Instillation of killed cells of S. mutans into the right parotid salivary duct elicited good IgG, IgA, and IgM responses in both the right parotid saliva and serum, but only a weak IgM response was detected in the left parotid saliva. Administration of killed cells of S. mutans in enterically coated capsules did not elicit a detectable antibody response or have a discernible effect on the antibody response to subsequent immunization by instillation. No increase in antibody titer was detected in the serum or whole saliva from monkeys orally immunized with enterically coated capsules containing viable S. mutans or in the serum, whole saliva, or intestinal contents from monkeys immunized with uncoated capsules containing killed cells of the same organism. These results do not support the concept that oral immunization with S. mutans is effective in stimulating a generalized secretory IgA response in primates.