Chlamydia psittaci infection in lines of mice with high or low antibody responses

Biozzi's high (H) and low (L) antibody producer mice were i.v. infected with a suspension containing 10(4)/ml viable C. psittaci organisms. H mice humoral anti-Chlamydia response was much higher than that of L mice. L mice natural resistance to infection with live Chlamydia was higher than that of H mice. Since the two lines exhibit inverse differences in B-cell and macrophage functions, but they are quite similar with regard to T-cell-mediated immunity, it would appear that macrophages play a more important and earlier role than humoral antibodies in resistance to chlamydial infection in H and L mice.