Long-term proliferation and survival of in vitro-activated T cells is dependent on Interleukin-2 receptor signalling but not on the high-affinity IL-2R.
Optimization of T-cell-activation protocols is an important prerequisite for the use of populations of activated, polyclonal T cells for immunotherapeutic purposes. This study compares two activation protocols. Following initial CD3/CD28 activation, naïve and memory subsets of CD8+ and CD4+ T cells were either repeatedly stimulated or maintained in medium containing interleukin-2 (IL-2). Initially, activation-induced cell death (AICD) was observed in all subsets. After 2-3 days, death in the cultures maintained in IL-2 only dropped dramatically, while live cells increased logarithmically. Despite intense proliferation, these cells lost the expression of CD25, the alpha chain of the IL-2 receptor and CD71, the transferrin receptor. Functional blocking of CD25 caused minimal changes in proliferation and survival of these cells as long as IL-2 was present in the medium. Blocking of CD25 in combination with the removal of IL-2 caused rapid death of these cells. Restimulation every 3-4 days led to persistently high levels of AICD and lower live cell counts. Live cells maintained the expression of activation markers and a blastoid phenotype. Initial CD3/CD28 followed by maintenance in IL-2 for 2-3 weeks seems to be the best in vitro T-cell-activation strategy. Signalling through the IL-2 receptor is vital for these cells, despite their downregulation of CD25.
Hedfors
I A
IA
Institute of Immunology, Rikshospitalet University Hospital, Oslo, Norway.
Brinchmann
J E
JE
D015703:Antigens, CD / Q000032:analysis; D000944:Antigens, Differentiation, B-Lymphocyte / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D002470:Cell Survival; D006801:Humans; D016130:Immunophenotyping; D037181:Lectins, C-Type; D017493:Leukocyte Common Antigens / Q000032:analysis; D008213:Lymphocyte Activation; D015375:Receptors, Interleukin-2 / Q000502:physiology*; D011990:Receptors, Transferrin; D015398:Signal Transduction / Q000502:physiology*; D013601:T-Lymphocytes / Q000502:physiology*; D000099192:CD69 Antigens
D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D000945:Antigens, Differentiation, T-Lymphocyte; D037181:Lectins, C-Type; D017493:Leukocyte Common Antigens; D015375:Receptors, Interleukin-2; D011990:Receptors, Transferrin; D000099192:CD69 Antigens; C068126:CD71 antigen