Naturally occurring prostate cancer antigen-specific T cell responses of a Th1 phenotype can be detected in patients with prostate cancer.
BACKGROUND
Cytotoxic T cells (CTL) are considered one of the primary effector cell populations in antitumor immunity. Recent studies, however, have demonstrated the critical importance of helper T cells (Th), specifically interferon gamma (IFN gamma)-secreting Th1 cells, either by supporting an appropriate CTL environment or by recruiting other effector cells. We evaluated whether patients with prostate cancer have naturally occurring Th-cell responses specific for two prostate cancer-associated antigens, prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP), and whether Th1-type responses to these antigens could be detected.


METHODS
Peripheral blood mononuclear cells (PBMC) were collected from 80 patients with prostate cancer and 20 male controls without prostate disease. Th-cell responses were evaluated by measuring antigen-specific proliferation. IFN gamma and IL-5 secretion in response to antigen stimulation was determined by enzyme-linked immunosorbent assay.


RESULTS
T cell proliferative responses specific for PSA and PAP could be detected in patients with prostate cancer. Six percent (5/80) of patients had T cell responses specific for PSA and 11% (9/80) for PAP. T cell responses specific for PSA were more prevalent in patients with metastatic disease (P = 0.02), whereas responses specific for PAP could be detected in patients irrespective of disease stage. IFN gamma-producing Th cells, specific for both PSA and PAP, could be identified in patients with prostate cancer.


CONCLUSIONS
Patients with prostate cancer can have detectable Th-cell responses specific for the prostate cancer-associated proteins PSA and PAP. The presence of antigen-specific Th1 immune responses in prostate cancer patients suggests that an immune environment capable of supporting antigen-specific CTL may exist in vivo. Prostate 47:222-229, 2001.
McNeel
D G
DG
Department of Medicine, Division of Medical Oncology, University of Washington, Seattle, Washington 98195-6527, USA. dmcneel@u.washington.edu
Nguyen
L D
LD
Ellis
W J
WJ
Higano
C S
CS
Lange
P H
PH
Disis
M L
ML
D000135:Acid Phosphatase / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000097:blood / Q000378:metabolism; D015848:Interleukin-5 / Q000097:blood / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D010641:Phenotype; D017430:Prostate-Specific Antigen / Q000276:immunology*; D011471:Prostatic Neoplasms / Q000097:blood / Q000276:immunology* / Q000473:pathology; D018417:Th1 Cells / Q000276:immunology* / Q000378:metabolism
D018984:Epitopes, T-Lymphocyte; D015848:Interleukin-5; D007371:Interferon-gamma; D000135:Acid Phosphatase; D017430:Prostate-Specific Antigen