HUMORAL ANTIBODY AND LYMPHOCYTE BLASTOGENESIS RESPONSES IN BALB C, C3H/HEJ AND AKR/N MICE FOLLOWING EHRLICHIA-RISTICII INFECTION/

Three strains of mice, two susceptible to Ehrlichia risticii induced d isease (BALB/c and C3H/HeJ) and one resistant (AKR/N), were evaluated for the development of humoral and cell mediated immune responses foll owing infection with E risticii. The production of serum antibody was determined by indirect fluorescent antibody testing of sera from mice of each strain challenged with one of three different dose levels of E risticii. Antibody was assayed on days 7, 9, 12, 15 and 20 after inoc ulation. Cell mediated immune responses were evaluated by measuring th e blastogenesis response of spleen cells from E risticii infected mice 28 days after inoculation. All three strains of mice at the high chal lenge level responded with the production of antibody by day 9 after i noculation. Overall, the antibody response occurred earlier and was of greater magnitude in the susceptible BALB/c and C3H/HeJ strains. A ma rked blastogenesis response occurred in splenocytes from E risticii in fected mice of all three strains upon re-exposure to ehrlichial antige n. The findings of this study indicate that susceptibility to E ristic ii induced disease was not the result of deficient or delayed humoral immune responses and that E risticii infection induced the development of strong cell mediated immunity.