A 70-KILODALTON RECOMBINANT HEAT-SHOCK-PROTEIN OF CANDIDA-ALBICANS ISHIGHLY IMMUNOGENIC AND ENHANCES SYSTEMIC MURINE CANDIDIASIS

The 70-kDa recombinant Candida albicans heat shock protein (CaHsp70) a nd its 21-kDa C-terminal and 28-kDa N-terminal fragments (CaHsp70-Cter and CaHsp70-Nter, respectively) were studied for their immmnogenicity , including proinflammatory cytokine induction in vitro and in vivo, a nd protection in a murine model of hematogenous candidiasis, The whole protein and its ma fragments were strong inducers of both antibody (A b; immunoglobulin G1 [IgG1] and IgG2b were the prevalent isotypes) and cell-mediated immunity (CMI) responses in mice. CaHsp70 preparations were also recognized as CMI targets by peripheral blood mononuclear ce lls of healthy human subjects, Inoculation of CaHsp70 preparations int o immunized mice induced rapid production of interleukin-6 (IL-6) and tumor necrosis factor alpha, peaking at 2 to 5 h and declining within 24 h, CaHsp70 and CaHsp70-Cter also induced gamma interferon (IFN-gamm a), IL-12, and IL-10 but not IL-4 production by CD4(+) lymphocytes coc ultured with splenic accessory cells from nonimmunized mice. In partic ular, the production of IFN-gamma was equal if not superior to that in duced in the same cells by whole, heat-inactivated fungal cells or the mitogenic lectin concanavalin A, In immunized mice, however, IL-4 but not IL-12 was produced in addition to IFN-gamma upon in vitro stimula tion of CD4(+) cells with CaHsp70 and CaHsp70-Cter, These animals show ed a decreased median survival time compared to nonimmunized mice, and their mortality was strictly associated with organ invasion by fungal hyphae, Their enhanced susceptibility was attributable io the immuniz ation state, as it did not occur in congenitally athymic nude mice, wh ich were unable to raise tither Ab or CMI responses to CaHsp70 prepara tions. Together, our data demonstrate the elevated immunogenicity of C aHsp70, with which, however, no protection against but rather some enh ancement of Candida infection seemed to occur in the mouse model used.