Interaction between Coxiella burnetii and guinea pig peritoneal macrophages

Abstract

The phagocytosis and subsequent degradation of phase I and II Coxiella burnetii by macrophages obtained from immune and nonimmune guinea pigs were compared. Phase I rickettsiae were more resistant to phagocytosis than were phase II organisms. There was no significant difference in the percentage of phagocytosis of either phase of rickettsiae by macrophages from immune or nonimmune animals. After ingestion, phase I and II organisms pretreated with normal serum multiplied and destroyed normal macrophages as well as macrophages obtained from guinea pigs immunized with phase II rickettsiae. In contrast, only phase I organisms were degraded by macrophages from phase I-immunized animals in the presence of normal serum. Immune serum rendered rickettsiae more susceptible to phagocytosis and also potentiated the destruction of organisms by all types of macrophages. The specificity of macrophages from phase I animals to degrade only phase I rickettsiae was demonstrated by the ability of Rickettsia rickettsii to replicate in these macrophages.

Appearance of cellular and humoral immunity in guinea pigs after infection with Coxiella burnetii administered in small-particle aerosols

“…Preparation of rickettsial stock suspension. The third egg passage of the Henzerling strain of C. burnetii in phase I was grown in chicken embryo cells as previously described (17). The infectivity of the rickettsial suspension was estimated to be 109.5 mouse median infectious doses after administration by the intraperitoneal route.…”

“…Previous in vitro studies indicated that homologous immune serum to phase I and II Coxiella burnetii not only enhanced the phagocytic uptake of rickettsiae (14)(15)(16)(17), but also potentiated their destruction within phagocytes (15)(16)(17). Although immune serum has not been shown to have a direct rickettsicidal action on C. burnetii, its passive transfer to nonimmune animals modifies the infection (1).…”

“…Recent studies indicate that cellmediated immunity (CMI) may play a role in C. burnetii infection. Peritoneal macrophages from guinea pigs previously immunized with phase I antigen are capable of killing phase I rickettsiae in the absence of homologous immune serum (16,17), and peripheral lymphocytes from humans who, for up to 8 years earlier, had been exposed to C. burnetii demonstrate marked lymphocyte transformation in vitro to both phase I and II C. burnetii antigens, even in the absence of circulating antibody (13). Therefore, it appears that CMI may be required for protection against Q fever infection.…”

Suppression of in vitro lymphocyte proliferation in C57BL/10 ScN mice vaccinated with phase I Coxiella burnetii

“…Macrophages are known to play a key role in the regulation of lymphocyte proliferation (33) and to mediate immunosuppression during numerous infectious diseases (18,35,44). Previous studies have shown that phase I C. burnetii WCV is readily phagocytized by macrophages and that this results in nonspecific activation of these cells (15,20). Preliminary experiments with prostaglandin synthesis inhibitors (9,32), macrophage toxins (22), cell-depletion techniques (10,13,33,38), and coculture protocols (37) suggest that the suppression and negative regulation of mouse spleen cells by phase I WCV may be mediated by T suppressor cells.…”

In vitro guinea pig leukocyte reactions to Rickettsia rickettsii

“…There are several reports on the CMI response against Coxiella burnetti. Heggers et al (10), Kishimoto and Burger (16), and Kishimoto and Walker (17) have described CMI events in guinea pigs, and Jerrells et al (11) have described the CMI response to C. burnetti infection in humans.…”