Artificial antigen-presenting cells plus IL-15 and IL-21 efficiently induce melanoma-specific cytotoxic CD8^+CD28^+ T lymphocyte responses

Objective:To develop a novel artificial antigen-presenting system for efficiently inducing melanoma-specific CD8+CD28+ cytotoxic T lymphocyte（CTL） responses.Methods:Cell-sized Dynabeads? M-450 Epoxy beads coated with H-2Kb:Ig-TRP2(181111K and anti-CD28 antibody were used as artificial antigen-presenting cells（aAPCs） lo induce melanoma-specific CD8*CD28’ CTL responses with the help of IL-2I and IL-I5.Dimer staining,proliferation,ELISPOT,and cytotoxicity experiments were conducted to evaluate the frequency and activity of induced CTLs.Results:Dimer staining demonstrated that the new artificial antigen-presenting system efficiently induced melanoma TRP2-specific CD8CD28' CTLs.Proliferation and ELISPOT assays indicated that the induced CTLs rapidly proliferate and produce increased IFN- y under the slimulalion of H-2K:Ig-TRP2-aAPCs,TL-15,and IL-21.In addition,cytoloxicily experiments showed lhat induced CTLs have specific killing activity of target cells.Conclusions:The new artificial antigen-presenting system including aAPCs plus IL-21 and IL-15 can induce a large number of antigen-specific CD8+CD28+ CTLs against the melanoma.Our study provides evidence for a novel adoptive immunotherapy against tumors.