Studies on Immune Response to <i>Mycobacterium lepraemurium</i>

Abstract

Evaluation of the cell-mediated immune response (CMI) in mice infected with Mycobacterium lepraemurium revealed a disturbance in the nonspecific components of the CMI. Expression of delayed type hypersensitivity (DTH) in skin test studies indicated that the organism is capable of inducing skin reactivity in mice. This begins at a very early stage of infection and subsequently decays as the infection becomes disseminated. At this stage, gross pathological changes are noticed followed by a high rate of mortality. An in vitro correlate of DTH, namely lymphocyte transformation, was in concordance with the observation on DTH. The suppression of CMI appears to be due to extensive multiplication of the infecting pathogen within the host system.

Deficit of interleukin 2 production associated with impaired T-cell proliferative responses in Mycobacterium lepraemurium infection

“…We have shown that proliferative responses to ConA and to allogeneic cells were depressed throughout MLM infection, whereas no significant modification in the generation of CTL could be detected. It has been well established that the inoculation of rats and mice with large doses of MLM or other pathogenic mycobacteria induces deficits of in vitro immune functions, such as responses to polyclonal T-cell mitogens (32,38) and specific antigens (21) and an impairment of in vivo T cell-mediated immunity, such as delayed skin graft rejection (6,23), reduced delayed-type hypersensitivity response to sheep erythrocytes (6), and T-dependent antibody response to sheep erythrocytes (5,25,38).…”

“…Since IL2 production is ILl dependent (20)(21)(22)(23)(24)(25)(26)(27)(28)(29), it could be hypothesized that the lack of ILl secretion by infected macrophages could play a role in the failure of IL2 production. Indeed, mouse strains susceptible to subcutaneous MLM inoculation display macrophage abnormalities, such as a diminished efficacity in controlling mycobacterial multiplication in vivo as compared with resistant mice (22) or an enhancement of superoxide dismutase activity in splenic macrophages of MLM receptive mice (30).…”

“…Susceptible mice infected either intravenously or intraperitoneally with large doses of MLM have been shown to display impaired specific and nonspecific T cell-mediated immunity both in vivo (23) and in vitro (21,22) and impaired T cell-dependent antibody responses to sheep erythrocytes (5,37).…”