Human leukocyte antigen subtype analysis in patients with advanced adenocarcinoma of the prostate

Relationship between HLA-DR antigen and HLA-DRB1 alleles and prostate cancer in Japanese men

PURPOSE

Human leukocyte antigens (HLA) are cell surface glycoproteins playing a key role in the immune system. In some cancers, changes in major histocompatibility complex (MHC) class I and II expression, usually a reduction or loss of these molecules, appear to provide a mechanism whereby tumour cells may escape host immunity. We investigated the relationship between HLA, especially class II, molecules and prostate cancer in Japanese men using molecular techniques.

MATERIALS AND METHODS

HLA class II typing was performed by the polymerase chain reaction-sequence specific primer (PCR-SSP) method of analysis and/or a commercial rapid assay based on the PCR followed by reverse dot-blot hybridization of the PCR products (Inno-LiPA assay). Allele frequencies were calculated. HLA allele frequencies reported in 1216 healthy Japanese individuals were used as the control data. Differences in allele frequency between subjects and the control group were analyzed by the chi-square test. The relationship between HLA antigens/alleles and prostate cancer is expressed in terms of relative risk (RR).

RESULTS

The frequencies of HLA-DR4 were significantly higher in Japanese men with prostate cancer than in the healthy control group (gene frequency 36.2% vs. 26.3% in control, p<0.05), although the relative risk of prostate cancer was less than 2. Furthermore, the frequencies of HLA-DRB1-0406, 0410 and 1405 allele were significantly higher in the prostate cancer group than in the control group (allele frequency was 7.3%, 4.5% and 5.4% vs. 3.03%, 1.79% and 2.22%, p<0.05, respectively). RR of those HLA-DRB1 allele for prostate cancer was 2.6 in each allele.

CONCLUSIONS

HLA molecules may be useful for the early detection of prostate cancer as a risk factor, and also for recognizing cancer activity by using them as a marker helpful in the choice of appropriate treatment by predicting prognosis.

Familial prostate cancer in four brothers

We identified a family of 4 brothers with prostate cancer. The proband was the second son who was seen at the Department of Urology, Gunma University, Gunma, Japan, in May 1995, with a chief complaint of dysuria. The serum level of PSA was high, and a prostate needle biopsy revealed a moderately-differentiated adenocarcinoma. Subsequently, a total prostatectomy was performed. The family history revealed that the fourth son had been under treatment at the Saitama Cancer Center Hospital for prostate cancer since 1994. Therefore, the other 2 brothers became healthy male family members of the familial prostate cancer line, and their serum PSA levels were examined after obtaining their informed consent. Both had a high serum PSA level and biopsies revealed moderately-differentiated adenocarcinomas in both. Human leukocyte antigen class II gene typing was conducted on 3 of 4 brothers and 4 healthy family members who gave informed consent, and revealed the DRB1*0901-DQB1*0303 haplotype in the first, second and third sons. Familial prostate cancer is well documented in Europe and the US where the incidence of prostate cancer is high, but this is the first report of prostate cancer in 4 brothers in Japan.

Report of immune monitoring of prostate cancer patients undergoing T-cell therapy using dendritic cells pulsed with HLA-A2-specific peptides from prostate-specific membrane antigen (PSMA)

BACKGROUND

In this paper we describe our program for the immune monitoring of phase II participants given dendritic cell (DC)/prostate-specific membrane antigen (PSMA)-based immunotherapy, and we also present some initial findings.

METHODS

Phase II subjects received six administrations of autologous dendritic cells exogenously pulsed with two peptides derived from PSMA. Prior to the initial infusion, and following each treatment, peripheral blood mononuclear cells (PBMC) were collected for the generation of dendritic cells as well as for comprehensive immune monitoring.

RESULTS

Thus far, an increase in PSMA-peptide-specific as well as overall cellular reactivity has been observed in several patients receiving DC plus PSM-P1 and -P2, as measured by delayed-type hypersensitivity (DTH) test and enzyme-linked immunosorbant assay (ELISA).

CONCLUSIONS

Our initial observations using an ELISA and DTH test indicate that we are enhancing cellular immunity in prostate cancer patients following infusion with DC plus PSMA-derived peptides. Several methods are underway to comprehensively monitor both cell-mediated and humoral immune responsiveness, including: determining anti-PSMA serum antibody titers, testing immunogen-restricted responder-cell proliferation and cytotoxicity, assessing aberrations in signal transduction, antigen processing, and presentation, and measuring soluble factors that may promote tumor outgrowth.

Induction of human cytotoxic T lymphocytes specific for prostate-specific antigen

Prostate-specific antigen (PSA), a tissue-specific protein expressed by most adenocarcinomas of the prostate, might be a useful target for T-cell-mediated immunotherapy of prostate cancers. The current study examined whether it is possible to elicit human cytotoxic T lymphocytes (CTL) with specificity for PSA. A synthetic nonamer peptide, corresponding to residues 146-154 of PSA and containing a canonical HLA-A2-binding motif, was shown to stabilize the expression of HLA-A2 on the T2 antigen-processing mutant cell line. Repeated in vitro stimulation of peripheral blood lymphocytes from a normal HLA-A2+ donor induced CTL with specificity for the PSA 146-154 peptide. The peptide-induced CTL expressed the CD4- CD8+ cell surface phenotype and were restricted by HLA-A2. A large portion of patients with prostate cancer express the HLA-A2 phenotype, implying that many prostate cancers might be targeted by HLA-A2-restricted CTL with specificity for the PSA 146-154 epitope.

Presentation of prostate tumor antigens by dendritic cells stimulates T-cell proliferation and cytotoxicity

Dendritic cells (DCs) are "professional" antigen-presenting cells capable of stimulating T-cell proliferation and cytotoxicity when loaded with and presenting specific antigens, including tumor antigens. We demonstrated the stimulation of an autologous cytotoxic T-cell response elicited by DC loaded with autologous tumor cell lysate derived from primary prostate tumor. A candidate tumor antigen is prostate-specific membrane antigen (PSMA), which is overexpressed in prostate cancer patients. We identified a HLA-A2 motif in PSMA, isolated patient DC, loaded peptide into DC, and stimulated autologous T cells to proliferate. The ability to use DC for presentation of either tumor or peptide antigen in an HLA-restricted fashion in order to stimulate T-cell proliferation and cytotoxicity demonstrates the potential of this technology for development of a prostate cancer vaccine.