The active form of vitamin D, 1,25(OH)2D3, can prevent various forms of experimentally induced autoimmune disorders. The aim of this study was to confirm these findings in NOD mice that spontaneously develop an autoimmune type of diabetes mellitus. Therefore, the effect of a long-term 1,25(OH)2D3 treatment on the incidence of insulitis, the histological lesion preceding diabetes, was studied. Forty-three NOD mice were treated with 1,25(OH)2D3 (5 micrograms/kg) i.p. every other day from age 21 days on, when no insulitis was present yet. At day 100, 16 control mice receiving the treatment vehicle (arachis oil) had an incidence of insulitis of 75%, whereas only 41% of the 1,25(OH)2D3-treated animals developed insulitis (P < 0.025). Calcemia, determined 24 h after the last 1,25(OH)2D3 injection was 2.5 +/- 0.1 mM, which was higher than in control animals (2.3 +/- 0.1 mM), but was well tolerated. Cellular immunity, as assessed with the mixed lymphocyte reaction performed at day 100, was not impaired significantly. This study demonstrates that long-term treatment with high doses of 1,25(OH)2D3 is able to decrease the incidence of insulitis in spontaneous autoimmune diabetes without major side effects.

Nude mice were inoculated with CHO/IFN-gamma cells, a line of Chinese hamster ovary tumor cells, that had been genetically engineered to produce murine IFN-gamma. Severe cachexia, as evident from body weight loss and reduced food intake, occurred in these mice, but not in those injected with CHO/control cells, i.e. the original, non-IFN-gamma-producing line. The essential role of IFN-gamma in the pathogenesis of cachexia was confirmed by the demonstration that monoclonal antibodies (MAbs) against IFN-gamma, given prior to injection of the tumor cells, prevented cachexia. In addition to IFN-gamma, the presence of the tumor cells was also required for cachexia to develop. As evident from pair-feeding experiments, reduced food intake could only partially account for the rapid and extensive body-weight loss. Cachexia was characterized by a marked reduction in the amount of interscapular fat tissue. Injected tumor cells exclusively invaded intraperitoneal adipose tissue and elicited an inflammatory cell infiltrate, indicating that interscapular fat loss was due to humoral factors. Our data suggest that, among the humoral factors responsible for cancer-associated cachexia, IFN-gamma plays a prominent role.

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