Analysis of in vitro lymphoproliferative responses and antibody formation following subcutaneous injection of Actinobacillus actinomycetemcomitans and Wolinella recta in a murine model

The potential of Wolinella recta and Actinobacillus actinomycetemcomitans to cause abscesses and induce an immune response was tested in BALB/c mice. Mice were injected subcutaneously with W. recta, A. actinomycetemcomitans or a mixture of these 2 microorganisms. Mice injected with A. actinomycetemcomitans alone, or with both organisms, demonstrated abscesses at the injection site 2 days later, from which pure cultures of A. actinomycetemcomitans were isolated. Mice injected with W. recta had small, flat abscesses at the injection site from which no bacteria could be cultured. W. recta was cultured from injection sites only when associated with A. actinomycetemcomitans. Mice developed positive serum IgG antibody responses to W. recta by 20 days post-injection but not to A. actinomycetemcomitans whether injected in pure culture or mixed infection. In vitro lymphoproliferative responses following injection of W. recta and/or A. actinomycetemcomitans resulted in increased lymphocyte reactivity in unstimulated cultures and decreased in vitro responses to phytohemagglutinin. In vitro lymphoproliferative responses to Escherichia coli LPS or Salmonella typhimurium LPS were depressed in mice injected with A. actinomycetemcomitans, but not in mice injected with W. recta.