Immunofluorescent studies of the local immune response in the mammary glands of rats.

Two irritants, phosphate-buffered saline and alcohol, and antigens including killed Brucella abortus, live B. abortus, Staphylococcus aureus, and rat parvovirus were separately infused into rat mammary glands during pregnancy, and by using immunofluorescent techniques, the numbers of immunoglobulin-containing cells in glands during lactation and involution were determined. The study provided basic information on the local immune response of the mammary gland to antigens of various types. In all experiments, the number of immunoglobulin M (IgM) cells present was small and no trends were apparent. IgA cells were always more prevalent than IgG cells. Fewer IgA cells were in the glands of rats infused with phosphate-buffered saline and alcohol than in normal rats. IgA cell prevalence was greatest in response to infusion of live B. abortus. Responses to live S. aureus and parvovirus were less pronounced, and infusion of killed B. abortus did not induce an elevation in IgA cell prevalence. IgG cell prevalence was greatest in response to infusion of live B. abortus or S. aureus and was decreasingly less pronounced in response to killed B. abortus and rat parvovirus. With the exception of parvovirus infusion, in regard to IgA cells, all glands locally infused with antigen had elevated IgA and IgG cell numbers when compared with noninfused glands in the same animal.