Bradley, David S.

Abstract We have previously demonstrated that inbred B10.T(6R) mice are resistant to Yesinia pestis (KIM5 strain) and resistance decreases with age. It has been shown that Y. pestis is cleared by neutrophil engulfment. We evaluate here the potential contribution of IL-1β, a proinflammatory cytokine important for neutrophil recruitment and activation. IL-1β levels were measured from spleens and sera collected 60 and 72 hour post infection from young (resistant) and middle-aged (susceptible) B10.T(6R) mice and control (susceptible) C57BL/6. Splenic IL-1β production was statistically higher in young B10.T(6R), compared with both middle-aged B10.T(6R) and C57BL/6 mice. Serum IL-1β levels were also moderately higher in young B10.T(6R) mice when compared to middle aged B10.T(6R) and C57BL/6 mice. IL-1β produced by Y. pestis-infected peritoneal-derived macrophages taken from uninfected young and middle-aged B10.T(6R) mice and C57BL/6 mice was measured at 2,4,8 and 24 hour. IL-1β levels were significantly elevated in peritoneal macrophages infected in vitro from young B10.T(6R) mice compared to decreased levels in both middle-aged B10.T(6R) and C57BL/6 derived peritoneal macrophages. These studies suggest a direct correlation between elevated IL-1β levels and resistance to Y. pestis infection observed in young B10.T(6R) mice.

Abstract We have generated transgenic (tg) mice expressing HLA-DQ8αβ (DQA1*0301/DQB*0302) or HLA-DQ6αβ (DQA1*0103/DQB1*0601) molecules lacking endogenous murine class II expression (Aβ0) to investigate the ability of these HLA class II to present type II collagen (CII) and induce collagen-induced arthritis. The DQ8αβ tg mice responded strongly to CII, developing severe arthritis, while DQ6αβ tg mice were nonresponsive to CII. The addition of the mixed haplotype DQ8α6β molecule did not significantly influence CII reactivity. To examine the interaction of DQ6αβ and DQ8αβ molecules in vivo, we generated double tg DQ6αβ/8αβ (Aβ0) mice expressing both the α- and β-chains of DQ6 and DQ8 molecules by mating DQ6αβ (Aβ0) and DQ8αβ (Aβ0) tg mice. CII-immunized DQ6αβ/8αβ tg mice developed severe experimental polychondritis, exhibiting both polyarthritis and auricular chondritis. The clinical, serologic, and histologic manifestations of experimental polychondritis are similar to those symptoms in human relapsing polychondritis. The susceptibility of DQ6αβ/8αβ tg mice compared with resistance in the parental strains suggests that expression of both the DQ6αβ and DQ8αβ tgs, unique to the DQ6αβ8αβ tg strain, is important in susceptibility to experimental polychondritis. The DQ6αβ/8αβ tg mice provide a model to investigate putative autoantigens and the mechanisms of pathogenesis involved in relapsing polychondritis as well as the influence of the expression of multiple HLA class II molecules on the disease process.