The process of T cell immune reconstitution post-chemotherapy in breast cancer patients is impaired. Such a deficit in T cell immunity likely represents an important obstacle to tumor vaccine therapy in breast cancer patients. In an attempt to enhance T cell immune reconstitution, we have administered cryopreserved T cells and interleukin-2 to breast cancer patients post-chemotherapy. Initial data from the first 13 patients enrolled on this study suggests that the administration of T cells and IL-2 resulted in improved T cell reconstitution relative to untreated patients or patients receiving only IL-2. Importantly, recipients of the combination of T cells and IL-2 had an enhanced recovery of CD4+CD45RA+ T cells; because this T cell subset represents a naive T cell phenotype that generally maintains a capacity to respond to antigen, enhanced regeneration of this population may result in improved immune function and may allow for a more successful immune response to tumor vaccines. It will be important to now evaluate what effect T cell administration alone (without IL-2 treatment) has on immune reconstitution post-chemotherapy. Determination of the relative benefits of T cell and/or cytokine administration on T cell recovery post-chemotherapy may assist in the development of breast cancer vaccine protocols where a T cell-mediated immune response may be necessary for optimal response to the vaccine.