Patients undergoing autologous Peripheral Blood Stem Cell Transplants (PBSCT) have a slow recovery of their functional immunologic activity. As an example, various immunologic responses to recall antigens are usually blunted after bone marrow transplant. Immunization with tetanus or diptheria toxiods does not result in the development of antigen specific T-cell responsiveness when administered during the first three months after transplant. It is likely that the T-cell immune response to a neoantigen such as KLH when measured by the delayed hypersensitivity response may also be defective in the early post-PBSCT stage. While the precise mechanisms of the immune defects are not known, they may reside within the afferent arm of the immune response at the level of the dendritic cell which is involved in antigen processing and presentation. The establishment of dendritic cell cultures from the peripheral blood of adult patients has raised the possibility of now using these cells as an immunotherapeutic agent to circumvent such immune defects in the afferent arm and provide a method to target and accelerate immune reconstitution. This study will compare the ability to immunize patients to the neoantigen KLH after recovery from an autologous PBSCT. Immunizations will be carried out by two methods. A group of 8 patients will be immunized with a series of three intradermal injections of the neoantigen KLH. The immune response to this antigen, which we predict will be low, will be assessed 2-4 weeks after the last immunization. These patients will also be immunized and assessed as the first group of patients. This study will compare the immune response in these two groups of patients and investigate whether an absent or attenuated immune response to KLH may be overcome by immunizing patients with dendritic cells pulsed with KLH.
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