Immunological responses to monoassociated Bifidobacterium longum and their relation to prevention of bacterial invasion.
After monoassociation of Bifidobacterium longum with germ-free BALB/c mice (nu/+, heterozygous to nu gene), B. longum was recovered (10(2)-10(4) viable units per organ) from the mesenteric lymph nodes, liver and kidneys for 2 weeks post intragastric inoculation, but not after 4 weeks and later. Cessation of bacterial translocation was not observed in monoassociated nude (nu/nu) mice. Anti-B. longum IgA antibody was detected by ELISA using B. longum cell wall antigen in bile from Week 1 and in ileac wall extract from Week 8 post-association in both nu/+ and nu/nu mice. Total IgA levels in bile, ileac wall extract and caecal contents were also elevated in both mice after monoassociation. Cell-mediated immunity measured by the footpad test and macrophage migration inhibition test using B. longum protein fraction was detected in nu/+ mice in Week 4 and later, but not in nu/nu mice. Nu/nu mice reconstituted 4 weeks prior to monoassociation with lymphocytes from flora bearing nu/+ mice developed delayed footpad reactivity and bacterial translocation stopped after 4 weeks. Cell-mediated immunity rather than IgA antibody correlated well with the cessation of translocation.
D000193:Actinomycetales Infections / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D000942:Antigens, Bacterial / Q000276:immunology*; D001644:Bifidobacterium / Q000276:immunology*; D005260:Female; D005856:Germ-Free Life; D007111:Immunity, Cellular; D007116:Immunization, Passive; D007070:Immunoglobulin A / Q000032:analysis; D007071:Immunoglobulin A, Secretory / Q000032:analysis; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D007070:Immunoglobulin A; D007071:Immunoglobulin A, Secretory