Anomalous high native resistance to athymic mice to bacterial pathogens

Abstract

Congenitally athymic (nude) mice exhibited an anomalous high resistance against infections with the facultative intracellular parasite Listeria monocytogenes and other bacterial pathogens. Protection against lethal infection was demonstrated to result from the presence of naturally occurring activated macrophages in the reticuloendothelial organs of the nude mice. This was exemplified after intravenous challenge by enhanced bacterial clearance from the blood and augmented bacterial killing in the spleens and livers of nude mice as compared with immunologically competent control mice. Resident peritoneal macrophages ofnude mice were not activated in terms ofphagocytic, bactericidal, or tumoricidal potential. The development of activated fixed tissue macrophages appears to arise as a result of the T-lymphocyte deficiency since thymus implantation abrogated the enhanced resistance of nude mice. Antibiotic elimination of intestinal bacteria also modified resistance to bacterial infection, indicating a role of environmental factors on macrophage activation. Several possible mechanisms leading to macrophage activation and heightened resistance to infection in nude mice are offered.

Natural Immunity: A T‐Cell‐Independent Pathway of Macrophage Activation, Defined in the scid Mouse

“…In addition, bacterial loads in the early stages of infection were from 4 to 130-fold lower in 5aV/versus C.B-17 mice. Similar chronic infection has also been observed in athymic nude mice (Emmerling et al 1975, Cheers & Waller 1975, Nickol & Bonventre 1977 and following depletion of CD4 and CD8 T cells in immunocompetent mice (Sasaki et al 1990). Thus, in the absence of antigen-specific immunity, T cell-independent processes partially controlled replication of Listeria in vivo.…”

Viral Diseases of the Digestive System

“…It was not until Sebesteny and Hill (1974) UV-inactivated virus did not elicit the effect. The authors be lieve that fixed macrophages in athymic mice may be acti-vated, as was indicated by Nickol and Bonventre (1977) and by Cheers and Waller (1975) in certain bacterial infections in nude mice. T a m u r a et aL (1979) (see, e .…”

Immunopathology of Chronic Progressive Hepatitis in Nude Mice Infected with Low‐Virulent Mouse Hepatitis Virus

“…Most of these cells were considered to be NK cells reacting to MHV (32,33) and playing important roles in the host defense during the early stage of MHV infection. The activity of macrophages and NK cells were shown to be enhanced after infection with some bacteria and viruses in nu/nu as well as nul + mice (17,20,25,35). By IF as well as flow cytometry, the number of Thy-l-positive cells were shown to increase in the spleen and liver of infected flu/flu mice, as described with naturally (24) and experimentally (30,31) infected nu/nu mice.…”