Shock Fusion Protein Recombinant Differentiation in Response to a T Cell + Cell Activation and Cytolytic CD8 A Role for Toll-Like Receptor 4 in Dendritic

Recombinant heat shock fusion proteins (Hsfp) injected into mice without added adjuvants can stimulate production of CD8 cytolytic T cells. Because initiation of productive immune responses generally requires dendritic cell (DC) activation, the question arises as to whether the Hsfp can activate DC independently of contaminating LPS. Using microarray analyses of DC from LPS-insensitive mice having a point mutation in Toll-like receptor 4 (Tlr4) (C3H/HeJ), or lacking Tlr4 (B10/ScNCr), we show here that unlike a LPS standard, Hsfp activated DC from HeJ mice almost as well as DC from wild-type mice. Consistent with the microarray analysis, the Hsfp’s ability to activate DC was not eliminated by polymyxin B but was destroyed by proteinase K. The Hsfp did not, however, stimulate DC from mice lacking Tlr4. In vivo the CD8 T cell response to the Hsfp in mice lacking Tlr4 was impaired: the responding CD8 cells initially proliferated vigorously but their development into cytolytic effector cells was diminished. Overall, the results indicate that this Hsfp can activate DC independently of LPS but still requires Tlr4 for an optimal CD8 T cell response. The Journal of Immunology, 2004, 172: 2885–2893. P revious studies have shown that mice injected with various heat shock fusion proteins (Hsfp) 4 made by linking protein domains or polypeptides to mycobacterial heat shock proteins stimulate the production of cytolytic CD8 T cells that recognize peptides derived from the Hsfp’s fusion component (1–4). A compelling body of evidence indicates that the initiation of immune responses requires activation of dendritic