Phorbol dibutyrate and ionomycin improve murine effector cell cytotoxicity.
Simultaneous protein kinase C stimulation with phorbol 12,13-dibutyrate (PDBU) and calcium mobilization with ionomycin (Io) trigger cellular events leading to expression of proliferation-associated genes in human lymphocytes. The effect of a 16-hr exposure to PDBU and Io on the growth and cytotoxic activity of murine splenocytes and tumor-infiltrating lymphocytes (TIL) cocultured with interleukin-2 (IL-2) was studied. PDBU + Io increased the number of cytotoxic effector cells that could be generated in lymphokine-activated killer cells (LAK) cultures (40-fold) and to a lesser extent in TIL (10-fold). DNA synthesis of TIL increased significantly when exposed to PDBU + Io. Also, TIL stimulated with PDBU + Io demonstrated in vitro tumor-specific lytic activity significantly greater than that of control TIL (500 lytic units vs 50). The cell-surface phenotype of TIL treated with PDBU + Io was identical to that of control TIL (> 95% CD-3+, CD-4-, CD-8+). Results of adoptive immunotherapy using splenocytes stimulated by PDBU + Io and cultured in IL-2 were identical to those achieved when standard LAK cultures were used. However, treatment using TIL stimulated by PDBU + Io led to a significant reduction in the number of pulmonary nodules compared to standard TIL. In addition, PDBU + Io-stimulated TIL maintained significant in vivo activity without the need for systemic IL-2 administration. Pharmacologic manipulation of cytotoxic precursor cells is a useful strategy for improving the generation of murine cytotoxic effector cells. By using PDBU + Io, cytotoxic lymphocytes could be generated with improved in vitro and in vivo activity.
Hamby
L S
LS
University of Kentucky, Department of Surgery, Lexington 40536-0084.
Freeman
J W
JW
McGrath
P C
PC
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D005260:Female; D016219:Immunotherapy, Adoptive; D015759:Ionomycin / Q000494:pharmacology*; D015979:Killer Cells, Lymphokine-Activated / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D008175:Lung Neoplasms / Q000556:secondary / Q000628:therapy; D016246:Lymphocytes, Tumor-Infiltrating / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009368:Neoplasm Transplantation; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology*
D015240:Phorbol 12,13-Dibutyrate; D015759:Ionomycin