Cellular immune response to Listeria in genetically resistant and susceptible mouse strains.

Relatively Listeria-resistant C57B1/6 mice and more susceptible to the infection DBA/2 mice were immunized with Listeria-antigen (LA). Immunized DBA/2 mice developed weaker delayed hypersensitivity to LA and still eliminated listeriae less effectively than identically immunized C57B1/6 mice. An accessory function of LA-pulsed macrophages of normal C57B1/6 mice was only slightly enhanced as compared with LA-pulsed macrophages of DBA/2 mice. It is suggested that some suppressor lymphocytes, IgM+ and/or FcR+, could be responsible for the enhanced susceptibility of DBA/2 mice to listeriosis.