HOZOTs, novel human regulatory T-cell lines, exhibit helper or suppressor activities depending on dendritic cell or anti-CD3 stimulation.
OBJECTIVE
HOZOT cell lines (HOZOTs) are a new type of regulatory T cells established from human umbilical cord blood without using cytokines. In addition to their unique FOXP3(+)CD4(+)CD8(+)CD25(+) phenotype, HOZOTs are bifunctional and can exert either suppressor or cytotoxic activities. To further characterize HOZOTs, we cocultured HOZOTs with responder T cells under different stimulation conditions and found another function of HOZOTs.


METHODS
Naïve CD4(+)T cells as responder cells were stimulated with dendritic cells or plate bound anti-CD3 antibody. As effector cells, HOZOTs were added to this culture and proliferation of the responder cells were monitored by (3)H-thymidine incorporation or carboxyfluorescein succinimidyl ester dilution method. To investigate the molecular mechanisms, antibodies specific for interleukin (IL)-2/IL-2R or cell surface molecules were used for blocking experiments.


RESULTS
The proliferation of naïve CD4(+)T cells was suppressed by one HOZOT line, HOZOT-4, when the responder cells were stimulated with dendritic cells. However, responder cell proliferation was augmented by HOZOT-4 when these cells were stimulated with anti-CD3 antibody. This opposing function to responder cells was unique to HOZOTs because naturally occurring regulatory T cells suppressed proliferation of both dendritic cell- and anti-CD3-antibody-stimulated cells. IL-2 was not involved in the mechanism of the helper activity of HOZOT-4 as blocking antibodies for IL-2 and IL-2R did not abrogate the helper activity. Moreover, this helper activity could not be reduced by blocking costimulatory pathways such as CD28/B7, CD4/human leukocyte antigen-DR, and intercellular adhesion molecule-1/lymphocyte function-associated antigen-1.


CONCLUSIONS
We demonstrated a new function of HOZOTs as helper T cells in addition to suppressor and cytotoxic activities, characterizing HOZOTs as multifunctional T cells.
Sugimoto
Akira
A
Cell Biology Institute, Research Center, Hayashibara Biochemical Laboratories, Inc., Fujisaki, Okayama 702-8006, Japan.
Suzuki
Motoyuki
M
Otani
Takeshi
T
Okochi
Ayumi
A
Takeuchi
Makoto
M
Yamasaki
Fumiyuki
F
Nakamura
Shuji
S
Kibata
Masayoshi
M
D000906:Antibodies / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D018122:B7-1 Antigen / Q000378:metabolism; D017252:CD3 Complex / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D016827:CD8 Antigens / Q000378:metabolism; D060908:CTLA-4 Antigen; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D003602:Cytotoxicity, Immunologic / Q000187:drug effects / Q000276:immunology; D003713:Dendritic Cells / Q000166:cytology* / Q000276:immunology; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D007376:Interleukin-2 / Q000276:immunology / Q000378:metabolism; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D015847:Interleukin-4 / Q000276:immunology / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D006377:T-Lymphocytes, Helper-Inducer / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D050378:T-Lymphocytes, Regulatory / Q000166:cytology* / Q000276:immunology / Q000378:metabolism
D000906:Antibodies; D015703:Antigens, CD; D018122:B7-1 Antigen; D017252:CD3 Complex; D016827:CD8 Antigens; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; C508017:IL2RA protein, human; D007376:Interleukin-2; D053645:Interleukin-2 Receptor alpha Subunit; D015375:Receptors, Interleukin-2; D015847:Interleukin-4; D007371:Interferon-gamma