[Characterization of memory CD4+ IL-21+ T cells in human PBMC].
OBJECTIVE
To characterize IL-21-producing T cells in human PBMCs.


METHODS
PBMCs from healthy individuals were stimulated with or without anti-CD3 (OKT3), OKT3 coupled with anti-CD28, or PMA coupled with ionomycin. The cell subsets of IL-21-producing T cells were determined by FACS. PBMCs, CD4+, CD4+CD45RA⁻, CD4+ CD45RA+ or CBMCs were stimulated with PMA coupled with ionomycin. The phenotype of CD4+ IL-21+ T cells and the correlation of IL-21-producing CD4+; T cells with Th1, Th2, Th17 and Th22 cell populations were analyzed by FACS.


RESULTS
PMA and ionomycin induced the highest level of IL-21 production among the stimuli tested. CD4+ T cells but not CD8+ T cells mainly expressed IL-21. CD4+ IL-21+ T cells expressed CD45RO instead of CD45RA. Some of the CD4+ IL-21+ T cells expressed CCR6, CCR7 or CXCR5. CD4+ CD45RA⁻ T cells expressed much more IL-21 than CD4+ CD45RA+ T cells. Furthermore, CD4+ T cells from PBMCs but not CBMCs, expressed IL-21. Approximately 24% of CD4+ IL-21+ cells expressed IFN-γ. Less than 10% of CD4+ IL-21+ cells expressed IL-4, IL-17 or IL-22.


CONCLUSIONS
IL-21 is induced from human PBMCs following various polyclonal stimulations. The majority of IL-21-producing cells in PBMCs are memory CD4+ T cells. In addition, some of the CD4+ IL-21+ T cells are distinct from Th1, Th2 and Th17 cells.
Department of Immunology, Zhongshan School of Medicine, the Secondary Affiliated Hospital of Sun Yat-sen University, Sun Yat-sen University, Guangzhou 510080, China.
Yun
Y
Liu
Li
L
Li
Feng-yu
FY
Huang
Chang-you
CY
Wu
D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory; D016130:Immunophenotyping; D007371:Interferon-gamma / Q000096:biosynthesis; D020381:Interleukin-17 / Q000096:biosynthesis; D007378:Interleukins / Q000032:analysis / Q000096:biosynthesis*; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D000098546:Interleukin-21
D020381:Interleukin-17; D007378:Interleukins; D007371:Interferon-gamma; D000098546:Interleukin-21