Evaluation of Antibody Responses Elicited by Immunization of Mice with a Pneu-mococcal Antigen Genetically Fused to Murine HSP70 and Murine Interleukin-4

摘要

The heat shock (stress) protein HSP70 has been shown to be a potent stimulator of cellular immune responses. In order to determine whether HSP70 has the ability to stimulate antibody responses, we constructed and expressed fusion proteins consisting of murine HSP70 or murine interleukin (IL)-4 co-valently linked to a pneumococcal cell wall-associated protein antigen designated PpmA. Immunization of mice with the PpmA-HSP70 fusion protein (PpmA-70) failed to elicit an increased PpmA-specific serum antibody response. In contrast, mice immunized with PpmA fused to IL-4 (PpmA-IL4), or PpmA fused to both IL-4 and HSP70 (PpmA-IL4-70) fusion proteins elicited high levels of PpmA-specific antibody responses. These data suggest that HSP70 has a limited capacity to stimulate immune responses to heterologous antigens in vivo.