The Protective Immune Response to Heat Shock Protein 60 ofHistoplasma capsulatumIs Mediated by a Subset of Vβ8.1/8.2+ T Cells

Abstract

Immunization with recombinant heat shock protein 60 (rHsp60) from Histoplasma capsulatum or a region of the protein designated fragment 3 (F3) confers protection from a subsequent challenge in mice. To determine the T cell repertoire involved in the response to Hsp60, T cell clones from C57BL/6 mice immunized with rHsp60 were generated and examined for Vβ usage by flow cytometry and RT-PCR. Vβ8.1/8.2+ T cells were preferentially expanded; other clones bore Vβ4, -6, or -11. When Vβ8.1/8.2+ cells were depleted in mice, Vβ4+ T cell clones were almost exclusively isolated. Measurement of cytokine production demonstrated that nine of 16 Vβ8.1/8.2+ clones were Th1, while only three of 13 non-Vβ8.1/8.2+ clones were Th1. In mice immunized with rHsp60, depletion of Vβ8.1/8.2+, but not Vβ6+ plus Vβ7+, T cells completely abolished the protective efficacy of Hsp60 to lethal and sublethal challenges. Examination of the TCR revealed that a subset of Vβ8.1/2+ clones that produced IFN-γ and were reactive to F3 shared a common CDR3 sequence, DGGQG. Transfer of these T cell clones into TCR α/β−/− or IFN-γ−/− mice significantly improved survival, while transfer of other Vβ8.1/8.2+ clones that were F3 reactive but were Th2 or clones that were not reactive to F3 but were Th1 did not confer protection. These data indicate that a distinct subset of Vβ8.1/8.2+ T cells is crucial for the generation of a protective response to rHsp60.

Cryptococcus neoformans Gene Expression during Experimental Cryptococcal Meningitis

“…Although a second HSP12 has also been identified in the genomic DNA sequence of strain B3501, no SAGE tag was identified in the serotype D in vitro temperature data. A SAGE tag for heat shock protein 60 (Hsp60p) was also identified; this protein is known to produce a strong immune response in the host during infection with Coccidioides immitis (87) and Histoplasma capsulatum (78). Studies of H. capsulatum demonstrate the use of Hsp60p and fragments of this protein as an effective vaccine (25).…”

A Deficiency in Gamma Interferon or Interleukin-10 Modulates T-Cell-Dependent Responses to Heat Shock Protein 60 fromHistoplasma capsulatum

“…The efficacy of this immunogen is dependent on the presence of CD4 ϩ T cells and endogenous gamma interferon (IFN-␥), interleukin 12 (IL-12), and IL-10 (8). Subsequent analysis of the T-cell receptor (TCR) repertoire in C57BL/6 mice has demonstrated that CD4 ϩ V␤8.1/8.2 ϩ cells are preferentially expanded following immunization with recombinant hsp 60 (rhsp 60) and are essential for the generation of protective immunity to this antigen (27). Elimination of this subpopulation of T cells blunts vaccine-induced immunity.…”

“…Elimination of this subpopulation of T cells blunts vaccine-induced immunity. Among V␤8.1/8.2 ϩ T-cell clones, only the population that produces IFN-␥ and responds to the protective fragment from hsp 60 confers protection upon adoptive transfer into TCR ␣/␤ Ϫ/Ϫ mice (27). The cellular and molecular factors that are important in immunity associated with vaccination with rhsp 60 have been identified independently (8,27).…”

Antigen-Presenting Dendritic Cells Rescue CD4-Depleted CCR2−/−Mice from LethalHistoplasma capsulatumInfection

“…For experiments in which H. capsulatum soluble cell wall membrane and cell wall (CW/M), heat shock protein 60 (HSP60), or ovalbumin (OVA) (Sigma-Aldrich, St. Louis, MO) was used as a source of antigen, the concentration used was 5 g/ml. CW/M and HSP60 from H. capsulatum were prepared as previously described (17,39); CW/M is composed principally of glycoproteins. CD4 ؉ T-cell depletion.…”