Ingestion of yogurt containing Lactobacillus acidophilus and Bifidobacterium to potentiate immunoglobulin A responses to cholera toxin in mice.

Lactic acid bacteria have been reported to have benefits for the prevention and treatment of some forms of diarrhea and related conditions. To determine whether these effects might involve direct stimulation of the gastrointestinal immune response, we administered yogurt to try to enhance mucosal and systemic antibodies against an orally presented immunogen, cholera toxin. Yogurts were manufactured with starter cultures containing different species and strains of lactic acid bacteria. Mice were fed these yogurts for 3 wk, during which they were also orally immunized twice with 10 micrograms of cholera toxin. Blood was collected on d 0 and 21, and fecal pellets were collected weekly. Mice that were immunized orally with cholera toxin responded by producing specific intestinal and serum immunoglobulin (Ig)A anti-cholera toxin. Antibody responses of the IgA isotype were significantly increased in mice fed yogurts made with starters containing the conventional yogurt bacteria Lactobacillus bulgaricus and Streptococcus thermophilus supplemented with Lactobacillus acidophilus, Bifidobacterium bifidum, and Bifidobacterium infantis. Yogurt that was manufactured with starters containing only conventional yogurt bacteria produced less IgA anti-cholera toxin than did the control group fed nonfat dry milk. Although strong responses were also observed for IgG anti-cholera toxin in serum, the responses did not differ among groups. Thus, administration of yogurt supplemented with L. acidophilus and Bifidobacterium spp. enhanced mucosal and systemic IgA responses to the cholera toxin immunogen.

Production of polyclonal antibody against ergosterol hemisuccinate using Freund's and Titermax adjuvants.

Ergosterol is the principal sterol in fungi and an important component of cell membranes. This sterol has been used previously to measure fungal growth in foods. In an attempt to develop antibodies for an immunoassay for ergosterol, we first derivatized the compound to its hemisuccinate (Erg-HS) and conjugated it to bovine serum albumin (Erg-HS-BSA). Six white female New Zealand rabbits were immunized by subcutaneous injections of Erg-HS-BSA conjugate followed by four booster injections. Freund's and Hunter's TiterMax adjuvants were used for stimulating strong and prolonged responses. An indirect enzyme-linked immunosorbent assay (ELISA) was used to assess the titers. Antibody titers to Erg-HS rose much earlier and were markedly higher when Freund's adjuvant was used than when TiterMax was used. Although titers as high as 6,400 were detectable by indirect ELISA, binding of these antibodies to an Erg-HS-BSA solid phase could not be inhibited by free ergosterol in a competitive indirect ELISA. The antibody was also evaluated for applicability in an enzyme-linked immunocytochemical assay for a variety of fungi but failed to detect the presence of ergosterol in the membranes of these organisms. Thus, although antibodies could be generated that showed high specificity for the Erg-HS-BSA conjugate, they could not detect free ergosterol.