Characterization of lung squamous cell carcinoma-derived T-cell suppressive factor.
BACKGROUND
The immunosuppressive state of a tumor-bearing patient is possibly mediated by tumor-derived factor. In this study, the authors characterized lung squamous cell carcinoma-derived immunosuppressive factor (LSCF).


METHODS
The immunosuppressive activity of QG56 (a lung squamous carcinoma cell line)-derived LSCF was evaluated by the effect of culture supernatant of QG56 on anti-CD3 monoclonal antibody-induced T-cell, response such as proliferation (3H-thymidine uptake), cytotoxicity (51Cr-releasing assay), and expression of cytokine mRNA (polymerase chain reaction). The LSCF was partially purified with an ion-exchange high-performance liquid chromatography (HPLC) and a gel-filtration HPLC.


RESULTS
The LSCF inhibited proliferation, cytotoxicity, and expression of cytokine mRNA of T-cells in a dose-dependent manner. It has a molecular weight of approximately 22 kd, and was sensitive to proteinase K, heating at 60 degrees C, and resistant to treatment with trypsin and pH 3 and 9. These properties appear to be similar to those of transforming growth factor-beta (TGF-beta). However, the activity of the LSCF was not abrogated by anti-TGF-beta sera, and the LSCF did not suppress the proliferation of TGF-beta-sensitive mink lung cells (Mv1Lu).


CONCLUSIONS
These data suggest that LSCF may be a novel tumor-derived immunosuppressive protein factor.
Yoshino
I
I
Department of Virology, Kyushu University, Fukuoka, Japan.
Yano
T
T
Miyamoto
M
M
Yamada
K
K
Kajii
Y
Y
Onodera
K
K
Ishida
T
T
Sugimachi
K
K
Kimura
G
G
Nomoto
K
K
D001483:Base Sequence; D017252:CD3 Complex / Q000276:immunology; D002294:Carcinoma, Squamous Cell / Q000276:immunology* / Q000378:metabolism; D016207:Cytokines / Q000235:genetics; D003602:Cytotoxicity, Immunologic; D017931:DNA Primers; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D008175:Lung Neoplasms / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012333:RNA, Messenger / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D013491:Suppressor Factors, Immunologic / Q000378:metabolism / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000502:physiology; D014407:Tumor Cells, Cultured
D017252:CD3 Complex; D016207:Cytokines; D017931:DNA Primers; D007376:Interleukin-2; D012333:RNA, Messenger; D015375:Receptors, Interleukin-2; D013491:Suppressor Factors, Immunologic; D016212:Transforming Growth Factor beta