Local and systemic immune response in aged hamsters.

Immunoglobulin levels in serum and saliva were measured in 2-3-month-old hamsters and in approximately 2-year-old hamsters. Salivary IgA concentrations in aged hamsters were slightly, but not significantly, higher than in young hamsters. Salivary volumes were generally greater in aged hamsters, resulting in a significantly increased total amount of IgA secreted per unit time. Serum IgG levels were somewhat elevated in aged hamsters while serum IgM levels were generally higher in the young hamsters. Serum IgA levels were markedly elevated in aged hamsters. Immune responses to the soluble protein enzyme, glucosyltransferase, from Streptococcus mutans strain 6715, were measured after injection of this antigen incorporated into Freund's complete adjuvant in the salivary gland vicinity. Salivary IgA responses were measured by an ELISA procedure and were lower in aged hamsters compared with young hamsters, after primary or secondary immunization. The serum IgG, IgA and IgM antibody responses were in general not significantly different between the two groups of animals. Sera from young and aged hamsters did not differ in their capacity to inhibit the ability of GTF to synthesize glucan from sucrose.