Selection and expansion of T cells from untreated patients with CLL: source of cells for immune reconstitution?

Background Lymphocyte-derived malignancies can be treated with combinations of drugs that efficiently eradicate normal and malignant lymphocytes. Lack of T lymphocytes after treatment of B lymphocyte CLL (B-CLL) makes the pat ients susceptible to serious infections and may limit the benefit of the th erapy. The aim of the study was to purify and culture-expand normal T lymph ocytes from B-CLL patients prior to therapy. These cells could be frozen an d given to the patients in the period post-chemotherapy. Methods T lymphocyte were isolated from the mononuclear cell apheresis prod ucts from five patients with previously untreated B-CLL. The apheresis prod ucts were red-cell depleted by density gradient centrifugation. B-lymphocyt e purging was performed by incubating with MAbs to four different B-cell ep itopes, followed by magnetic-bead depletion. One round of negative selectio n removed >90% of the B lymphocytes. The T-lymphocyte enriched cell suspens ion was cultured for 10/11 days in the presence of IL-2 and the anti-T cell receptor Ab OKT3. In addition, in some cultures anti-CD22 ricin immunotoxi n was added. Results T cells from CLL patients expanded 4.7-21-fold over a 10/11 days cu lture interval. After culture, CLL cells could no longer be identified by f low cytometric evaluation. The cultured T lymphocytes were predominately CD 8+, and were capable of lysing autologous CLL cells through a fas-dependent mechanism. Discussion Selection and expansion of T lymphocytes by this method may repr esent a strategy for enhancing immunity in the lymphocytic period following CLL treatment.