Detection of blood group A and H-related antigens in normal and neoplastic bladder epithelium: a comparative study using monoclonal antibodies with defined fine specificities

Three monoclonal anti-blood group H and four monoclonal anti-blood group A antibodies directed at the blood group antigens on Type 1 or Type 2 backbone structures were evaluated as immunohistochemical reagents by indirect immunofluorescence of normal and neoplastic bladder epithelia. The results were compared with fluorescence using polyclonal rabbit anti-A or H sera or Ulex europaeus lectin. The monoclonal antibodies gave less intense or more restricted immunofluorescence than the conventional reagents but showed considerable variation in the extent of their reactivities with urothelial samples from different individuals. In some cases they failed to give immunofluorescence with tissue samples known to contain the immunodominant blood group structures they recognize. In addition, hitherto unsuspected heterogeneity was revealed in the expression of the Type 2-based blood group H and A-structures in the endothelia of neighbouring small blood vessels.

[Establishment and characterization of a human ureteral cancer cell line producing carbohydrate antigen 19-9 and carcinoembryonic antigen]

We established a new cell line (FU-UrC-1) derived from a human primary ureteral carcinoma xenografted in a nude mouse. This cell line exhibited epithelial characteristics and formed clusters in monolayer cultures. The cells were subcultured in vitro for more than 20 passages and had a doubling time of 53 hours. The modal number of chromosomes was 66. The cell line, which was xenografted again to nude mice, produced tumors essentially identical to the original tumor. Furthermore, the cultured cells expressed carbohydrate antigen 19-9 (CA19-9) and carcinoembryonic antigen (CEA) that were secreted in the culture media. This cell line appears to provide a useful system for studying ureteral carcinoma in vivo and in vitro.

Characterization of MBT-2 tumour cell "variant" resistant to tumour necrosis factor

Previously we reported sensitivity of MBT-2 murine bladder tumour to tumour necrosis factor (TNF) in vivo and in vitro [8]. We showed that with prolonged exposure of cultured MBT-2 tumour cells to TNF, a resistant MBT-2 "variant" tumour cell population emerged in vitro. This concurred with the finding of transient in vivo cytotoxic effect of TNF against MBT-2 tumour. Herein, we delineate phenotypic changes in MBT-2 cells associated with TNF resistance. Parent MBT-2 (MBT-2P) and the TNF-resistant "variant" MBT-2R cells were compared in terms of in vitro sensitivity to TNF, DNA profile, karyotype and in vitro growth kinetics. We conclude that acquisition of resistance to TNF may be due to cell cycle derangement and differences in in vitro growth characteristics. DNA indices and karyotype of "variant" MBT-2R cells were not altered, indicating the anti-tumour action of TNF is not-mutagenic.

Impaired interferon-alpha production in whole-blood cultures from bladder cancer patients

Interferon-alpha (IFN-alpha) production was investigated in whole-blood cultures of 66 bladder cancer patients and 65 control subjects. IFN synthesis was induced with Sendai virus, and IFN activity was assayed in FL cells challenged with vesicular stomatitis virus (VSV). The mean levels of the IFN-alpha produced were 5,724 +/- 2,288 IU/ml in the control subjects and 4,800 +/- 2,353 IU/ml in the bladder cancer patients. IFN-alpha production was significantly suppressed in the bladder cancer patients compared with that in the control subjects (P less than 0.05). The impairment in IFN-alpha production correlated with the tumor grade, and it was shown that the tendency toward decreased IFN-alpha production was closely associated with the advancement of the tumor stage. Our results suggested that the decreased IFN-alpha production may contribute to the disordered immunoregulation in bladder cancer patients.

Combined effect of interleukin 2 and bacillus Calmette-Guérin in the therapy of mice with transitional cell carcinoma

We investigated the effect of combination therapy with interleukin 2 (IL-2) and Bacillus Calmette-Guérin (BCG) on C3H/HeN mice implanted with mouse bladder tumor cells (MBT2). MBT2-bearing mice were treated with a local injection of BCG into the tumor at a dose of 1 mg/day for a total of 3 times and/or a 10-day continuous subcutaneous infusion of 5 x 10(4) units IL-2/day from day 11 to day 20. As a result, the growth of the tumor in mice treated with IL-2 alone was slightly suppressed, while tumor growth was hardly suppressed in mice treated with BCG alone. However, when IL-2 was administered with BCG, tumor growth was strongly suppressed and mean survival time was prolonged. Natural killer cell activity in the spleen cells was most elevated in mice treated with IL-2 and BCG, while lymphokine-activated killer cell activity was not observed in all groups. Lymphocyte subset analysis showed that there was little change in the ratio of Lyt2-positive lymphocytes or that of L3T4-positive lymphocytes. These findings suggested that clinical evaluation of combination therapy with IL-2 and BCG may be worthwhile.

[Prognostic markers in transitional carcinoma of the bladder]

Due to the diversity of the biologic behaviour of the low-grade and low-stage superficial bladder carcinomas, particularly those that present a high recurrence rate, most of the research has been oriented towards finding prognostic markers of recurrence and future invasion of the tumor. Among these markers there are two that have demonstrated their usefulness: the study of the contents of the cellular DNA by flow cytometry and the study of blood group antigens. The latter are carbohydrate structures that form a complex, genetically-regulated signal code which intervenes in the cellular growth and maturation processes. Recently published works describing genetic alterations in transitional bladder carcinomas, oncogenic mutations, loss of the 9q chromosome that regulates the formation of A and B antigens, support the hypothesis that in neoplastic transformation processes, genetic alterations cause enzymatic deficiencies and disorders, and these produce several antigenic changes of the cellular membrane and thus interfere in the biologic behaviour of the malignant cell.

Keyhole limpet hemocyanine can enhance the natural killer activity of patients with transitional cell carcinoma of the bladder

It has been shown that natural killer (NK) cells are involved in the immunosurveillance of tumors. In patients with transitional cell carcinoma (TCC) of the bladder, there is a negative correlation between the levels of NK activity in peripheral blood mononuclear cells (PBMNCs) and both the clinical evolution and the pathological stages of the disease. We have investigated the immunoregulatory effect of keyhole limpet hemocyanin (KLH) on the NK activity of patients with TCC of the bladder. We found that KLH enhances the cytotoxic activity of PBMNC from patients with superficial TCC against NK-sensitive target cells in a time-dependent manner. This KLH-enhanced cytotoxicity is not directed against NK-resistant target cells. However, KLH fails to normalize the depressed NK activity of PBMNCs from patients with infiltrative TCC. The present in vitro studies suggest that this immunoregulatory effect of KLH on NK cytotoxicity may be implicated in its therapeutic effect on superficial TCC of the bladder.

Reduced LAK cytotoxicity of peripheral blood mononuclear cells in patients with bladder cancer: decreased LAK cytotoxicity caused by a low incidence of CD56+ and CD57+ mononuclear blood cells

The cytotoxicity of unstimulated peripheral blood mononuclear cells (US-PBMC), phytohemagglutinin (PHA)-stimulated PBMC (PS-PBMC) and interleukin-2 (IL-2)-activated PBMC (LAK cells) was assessed in patients with noninvasive and invasive transitional-cell bladder cancer and compared with those determined in healthy controls. The differences in the cytotoxicities were correlated with specific changes in the subsets of peripheral blood mononuclear cells (PBMC). PBMC from 37 patients and 13 healthy controls were tested against the bladder cancer cell line T24 in 51Cr-release assays. The PBMC subsets were analyzed using monoclonal antibodies against T cells, natural killer (NK) -cells, monocytes, and activation markers. The cytotoxicities of US-PBMC, PS-PBMC, and LAK cells were all significantly lower in the cancer patients than in the controls (P less than 0.05). The percentages of PBMC positive for the NK-cell markers CD56 and CD57 were lowest in the patients and were correlated to the decrease in cytotoxicity. Depletion of CD56+ or CD57+ cells from PBMC prior to or after 2 days stimulation with IL-2 demonstrated that these cells are the major source of LAK-cell cytotoxicity and showed that the reduced ability of bladder cancer patient PBMC to develop LAK-cell cytotoxicity is a result of a low incidence of CD56+ and CD57+ cells in the blood. These findings indicate that IL-2 therapy alone might not be a sufficient therapy of bladder cancer patients.

[Correlation of the expression of A, B isoantigens with its precursor H antigen in transitional cell carcinoma and the clinical signification of the expression]

The expression of ABO (H) isoantigens in tumors from 96 patients with transitional cell carcinomas (TCC) and the precursor H antigen of A or B antigens were studied by using immunohistochemical technique (ABC method). In our series ABO(H)isoantigens were demonstrated in 57 of 96(59.4%), grade I 76.5%, II 69.4% and III 33.3% respectively. The deletion of ABO(H) isoantigens was related statistically with the histologic grade of TCC (P less than 0.01) and the recurrence of the tumors (P less than 0.05). The results showed that the expression of the precursor H substance was very well related with the expression of A or B isoantigen (r = 0.99, P less than 0.001). The deletion of precursor H substance could more reliably predict the clinical course of the subsequent recurrence and mortality in A, B or AB type blood patients with TCC than that of A or B isoantigen. Detecting H substance can substitute completely detecting A or B isoantigen in tumors of A, B or AB type blood patients, and has more practical value clinically.

Reduction of major histocompatibility complex class I antigens on invasive and high-grade transitional cell carcinoma

We examined immunohistologically the expression of major histocompatibility complex (MHC) class I and II antigens, which play important roles in immune reactions, on transitional cell carcinoma (TCC). When stained with monoclonal antibody W6/32 against class I antigens, reduced staining was observed in 34 of 46 TCCs and was virtually absent in 15 of these. The cases showing reduced staining were much more frequent (29 of 34) in high- to moderate-grade than in low-grade TCC. Furthermore, class I antigens were reduced in 18 of 19 invasive TCCs, but in 16 of 27 superficial TCCs. Thus, the reduction of class I antigens was correlated significantly with a decreased degree of tumour cell differentiation and the presence of invasion. Class II antigens on TCC showed variable expression and were not related to tumour grade or stage.

Selective and non-selective loss of immunoregulatory molecules (HLA-A,B,C antigens and LFA-3) in transitional cell carcinoma

The expression of the major histocompatibility complex (MHC) class I and II antigens and lymphocyte function-associated antigen-3 (LFA-3) was investigated using immunohistochemical staining of bladder tissue sections from 18 patients with transitional cell carcinoma (TCC) and two normal bladder specimens. The expressions of HLA-A,B,C antigens varied greatly between different tumours. Complete loss was observed in one of 18 cases. Moderate to strong expression of HLA-A,B,C antigens was observed in 10 of 18 cases with the remaining seven cases showing either weak expression or expression on only a proportion of the tumour cells. Selective loss of HLA-Bw6 was seen in one of 18 cases. In many cases heterogenous and often focal expression of HLA-D products was seen. In one case tumour cells not expressing HLA-DR antigens were adjacent to strongly HLA-DR expressing non-neoplastic bladder epithelium, indicating a lack of inducible HLA-DR in the tumour cells. LFA-3 was undetectable in two of 18 cases with the remaining 16 cases showing moderate to strong expression of the molecule. These findings indicate that a substantial proportion of bladder tumours have one or more of a wide range of different alterations in the expressions of immunoregulatory molecules that could contribute to escape from immune surveillance.

[Production of monoclonal antibodies against human bladder cancer cells and application to immunohistochemical analysis of bladder cancer]

Two hybridomas secreting two monoclonal antibodies IgG1 B1.4 and IgG2a B1.6 were obtained by immunizing BALB/c mice with human bladder cancer cell line EJ-1. In immunohistochemical staining of cryopreserved tissues, B1.4 reacted with 0 of 9 grade 1 TCC, 6 of 11 grade 2, all of 6 grade 3 and five metastatic specimens. The antigen recognized by B1.4 was not expressed by normal urothelial cells but were expressed by vascular endothelial cells and muscle of tunica media. The target antigen of B1.6 was expressed by normal urothelial cells and all grade of TCC. In this study, it was demonstrated that poorly differentiated bladder cancer and metastatic specimens of bladder cancer express a vascular carbohydrate antigen. Taking the escape mechanism of immune surveillance, into consideration, it is possible that the antigen recognized by B1.4 is an indicator of metastatic potential of bladder cancer.

Bacillus Calmette-Guérin-treated superficial bladder cancer: correlation of morphology with immunophenotyping

Thirty-five biopsies from 19 patients with superficial transitional cell carcinoma of the bladder, treated with intravesical bacillus Calmette-Guérin (BCG), were assessed histologically and immunohistochemically. Pretreatment biopsies were available for comparison in all cases and five cases of non-specific cystitis were also examined. The inflammatory infiltrate was assessed with a streptavidin-biotin-peroxidase method using UCHL1, MT1, LN3, L26, HAM56, MAC387, Leu7 and anti-S100 in paraffin sections, and in 18 specimens were frozen tissues were available, Leu1, 2, 3, 4, 14, OKT10, HLA-DR and anti-Tac antibodies were applied. Post-treatment bladder biopsies showed severe oedema and a variable degree of inflammation. A granulomatous inflammation was seen in 11 cases, with granulomas present in six prostatic biopsies and acid-fast bacilli in two cases. The lymphoid infiltrate in all biopsies were largely T lymphocytes with a predominance of T helper cells present, often as a band-like infiltrate pressing against the residual epithelium, or the denuded bladder surface, and distributed in the vicinity of the granulomas. Activated lymphocytes were prominent in seven cases, although a moderate infiltrate of such cells was seen in all instances. Tac antigen was only occasionally expressed, and in a few NK cells were present among the infiltrates. In eight cases, HLA-DR was expressed in epithelial cells following BCG treatment, whereas all pre-treatment epithelial were negative.

Tumour-induced host stromal-cell transformation: induction of mouse spindle-cell fibrosarcoma not mediated by gene transfer

Tumour-induced host-cell transformation has been addressed by examining human tumours in situ and following xenograft to nude mice. We have found evidence for the transformation of host stromal fibroblasts both in vivo and following the introduction of the tumours to in vitro culture. The in vitro culture of one such xenograft--derived from a human prostatic adenocarcinoma--resulted in the outgrowth of a transformed aneuploid mouse cell line. This transformed line was tumourigenic both in BALB/c nu/nu (nude) mice and in heterozygous nu/+mice, with the morphology of a spindle-cell sarcoma. The cell line did not express human isozymes or human histocompatibility antigens, nor were human chromosomes present. Moreover, human DNA sequences were not detected by human Alu repeat sequence element probing in the transformed cell line grown either in vitro or in vivo. The line contained retroviral long terminal repeat sequences but there was no evidence of proviral activation. These findings indicate that tumour cells may cause transformation of neighbouring stromal cells; that this transformation may proceed in the absence of DNA transfer or activation of endogenous proviruses; and that the means of this observed transformation may involve humoral factors elaborated by the tumour cells.

Urinary cytokines following photodynamic therapy for bladder cancer. A preliminary report

This preliminary study was undertaken to test for the presence of urinary cytokines whose detection would provide evidence in support of the theory that photodynamic therapy (PDT) produces an immunologic response in patients treated for bladder cancer. Gamma interferon, interleukin 1-beta, interleukin 2, and tumor necrosis factor-alpha were assayed for in the urine of 4 patients treated with photodynamic therapy for bladder cancer, in 7 control patients undergoing transurethral surgical procedures, and in 5 healthy control subjects. Quantifiable concentrations of all cytokines, except gamma interferon, were measured in urine samples from the PDT patients with the highest light energies, while no urinary cytokines were found in the PDT patient who received the lowest light energy nor in any of the control subjects. These findings suggest that a local immunologic response may occur following PDT for bladder cancer.

[A transitional cell carcinoma of the urinary bladder with a high level of serum CA 19-9--a case report]

Reported is the case of a 72 year-old man who was hospitalized because of abdominal pain and gross hematuria. A subsequent laboratory examinations revealed a high level of serum CA 19-9, and abdominal computed tomography showed a mass lesion behind the urinary bladder and multiple lymphadenopathy. Examination of the digestive organs revealed no abnormality, however cystoscopy showed a submucosal a tumor with a partly ruddy surface. Thus, a percutaneous needle biopsy and a transurethral biopsy were performed. The pathological findings indicated a transitional cell carcinoma of the urinary bladder, and ABC-peroxidase staining revealed the presence of CA 19-9 positive cells in a portion of the carcinomatous cells.

Effects of local bacillus Calmette-Guerin therapy in patients with bladder carcinoma on immunocompetent cells of the bladder wall

The antitumoral effects of intravesical bacillus Calmette-Guerin against recurrent superficial urothelial bladder cancer seem to be linked to immunological effector mechanisms. To characterize further the local cellular response in the bladder wall of patients receiving intravesical bacillus Calmette-Guerin bladder biopsies were examined before and immediately after a 6-week course of bacillus Calmette-Guerin and for up to 1 year at 3-month intervals thereafter. The results showed a marked infiltration after bacillus Calmette-Guerin therapy predominantly of the suburothelial tissue with mononuclear cells, which expressed activation markers and accumulated to follicle-like granulomatous structures. With regard to T lymphocyte subsets the ratio of T helper-to-T suppressor cells in the bladder wall increased from 0.5 to nearly 2. This phenomenon persisted even in biopsies 1 year after initial treatment. In some probes activated mononuclear cells invaded the urothelium, emanating from suburothelial granulomas. It is tempting to assume that these changes within the local immunocompetent cells are related to the therapeutic effect of bacillus Calmette-Guerin against bladder cancer.

Immunohistochemical and immunocytochemical study of bladder carcinomas using the epithelium-specific, tumour-associated monoclonal antibodies HMFG1 and AUA1

The antigenic expression of normal bladder epithelium and transitional carcinomas has been studied using the epithelium-specific, tumour-associated monoclonal antibodies HMFG1 and AUA1. Tissues from 79 cases of bladder carcinoma and 11 cases of non-neoplastic bladder tissues were stained with both the haematoxylin-eosin (H/E) and the indirect two-stage immunoperoxidase methods using the monoclonal antibodies (MAbs) HMFG1 and AUA1 at a concentration of 25 micrograms ml-1. Positive and negative controls were also used. Moreover, 46 urine smears prepared after cytocentrifugation were stained with both the Papanicolaou and the indirect two-stage immunoperoxidase methods. The results showed that HMFG1 reacted with the majority of cases of grade III carcinomas and carcinomas in situ and with a subset only of low-grade (I and II) carcinomas. The pattern of staining showed the following characteristics: (1) the epithelial surface membrane stained both in normal bladder and bladder carcinomas (surface of the papillae), (2) a variant number of cancer cells, increasing with the degree of malignancy, showed membrane and/or cytoplasmic staining, (3) tumours of the same histological grade showed antigenic heterogeneity. The MAb AUA1 was not widely expressed. The immunocytochemical study confirmed the reaction of HMFG1 with a variant number of malignant urothelial cells exfoliated in urine. Their reaction with AUA1 was much more limited. The immunocytochemical staining seemed to be more sensitive in the detection of malignant cells in some cases which had been characterized as negative or suspicious for malignancy by the Papanicolaou examination. The intravesical treatment with chemotherapeutic agents did not seem to influence the antigenic expression of malignant urothelial cells.

Expression of CD15 antigen in urinary bladder transitional cell carcinoma

The biopsy specimens of 91 patients between the ages of 38 and 94 with transitional cell carcinoma of the bladder were retrospectively reviewed to determine if the expression of CD15 antigen detected by a monoclonal antibody MC2 was correlated with prognosis. Expression was variable, ranging from strong expression of the antigen by only the superficial cells in well differentiated papillary lesions to weak expression by most cells in solid or invasive tumours. In the invasive component there was a correlation between MC2 expression and tumour type, suggesting that the cell surface carbohydrate detected by MC2 may have a role in cell adhesion. There was no correlation between staining and survival. It is concluded that tumour type, grade, and stage remain the best prognostic indicators of urothelial tumours.

Elevations of cytokines interleukin-1, interleukin-2 and tumor necrosis factor in the urine of patients after intravesical bacillus Calmette-Guerin immunotherapy

In an attempt to elucidate further the immunological mechanisms responsible for the effectiveness of intravesical bacillus Calmette-Guerin in the therapy of superficial urothelial bladder cancer, a prospective study was performed in which the urine of patients was examined before and after 6 intravesical instillations of bacillus Calmette-Guerin for the presence of the cytokines interleukin-1, interleukin-2 and tumor necrosis factor-alpha. Biological assays such as specific sandwich enzyme-linked immunosorbent assays were used for the analysis of each cytokine. Urinary titers of interleukin-1, interleukin-2 and tumor necrosis factor increased significantly after bacillus Calmette-Guerin instillation but showed inter-individual differences. The maximum of secretion into the urine was seen between 4 and 8 hours after the instillation, and titers returned to baseline values within 24 hours. The differences in 24-hour secretion between the bacillus Calmette-Guerin-treated (10 patients) and the control (10) groups were significant with respect to all cytokines as tested in both assays each, except for the interleukin-1 biological assay. These results reflect the strong inflammatory response in the bladder wall to bacillus Calmette-Guerin, in which the urinary secretion of the detected cytokines may be associated with the local tumor control.

[Study of a monoclonal antibody against new epithelial membrane antigens of transitional cell carcinoma]

Immunizing mice with a transitional cell cancer (TCC) tissue in the renal pelvis, we produced a monoclonal antibody (EH14) against new epithelial antigens. After the mice were immunized repeatedly, their splenic cells were harvested and fused with NS/1 myeloma cells. The normal kidney tissue of the same patient was used on Dot blots to select the hybridoma. A a result, one hybridoma whose antibody (EH14) reacted very strongly with TCC but only faintly with normal kidney tissue or normal bladder mucosa was obtained. On immunohistochemistry, EH14 stained all of the 29 TCC tissues. EH14 also stained uterus cancer (7/7) and gastric cancer (6/6) as well as the normal squamous cell and many types of the normal epithelium. All of the lymphnodes containing metastatic bladder cancer were strongly stained with EH14. EH14, however, did not stain interstitial tissues, muscles and sarcomas. The molecular weight of the antigen recognized by EH14 was 14KD and 28 KD on Western blot analysis, and the antigen was stable with formalin or ethanol. The antigen was not the same as that reported previously, and may be useful as a histological marker of TCC.

Clinical studies on cell-mediated immunity in patients with urinary bladder carcinoma: blastogenic response, interleukin-2 production and interferon-gamma production of lymphocytes

Patients with advanced malignant neoplasms have a variety of abnormal lymphocyte functions. We examined the PHA blastogenic response, interleukin-2 (IL-2) production and interferon-gamma (IFN-gamma) production of lymphocytes in 39 bladder cancer patients and 20 control subjects. Correlation between these parameters was also studied. IL-2 production was measured by 3H-thymidine-labelled CTLL-2 assay, and IFN-gamma production was measured by immunoradiometric assay using 2 mouse monoclonal antibodies. As a result, in high stage bladder cancer patients, the PHA blastogenic response, IL-2 production and IFN-gamma production were impaired. However, these parameters were not significantly different between low stage bladder cancer patients and control subjects. There was a significant correlation between the PHA blastogenic response and IL-2 production but no significant correlation between the PHA blastogenic response and IFN-gamma production.

Clinical studies on bladder tumor-associated antigen in serum of patients with bladder cancer by using monoclonal antibody and sandwich ELISA

Investigations on tumor-associated antigen in the serum of patients with bladder cancer by using monoclonal antibody Hb 7A and sandwich ELISA were carried out on 36 patients with bladder cancer (BCa group), 18 patients with other tissue tumor (OTT group) and 22 normal subjects (control group). The average OD value of Hb 7A antigen of BCa group, OTT group and control group was 0.315 +/- 0.033, 0.124 +/- 0.026 and 0.12 +/- 0.021 respectively. The OD value of Hb 7A antigen in BCa group was significantly higher than that of control group and of OTT group (P less than 0.01), but there was no obvious difference between the control group and OTT group (P greater than 0.05). The positive detection rate in BCa group was 86% (31/36), while detection in all 22 normal subjects and the 18 patients of OTT group yielded negative results. The results indicated that the method of using McAb Hb 7A and sandwich ELISA, characterized by high specificity and sensitivity, is of value for clinical diagnosis and follow-up of patients with bladder cancer and general survey of persons at high risk of bladder cancer.

Flow cytometric evaluation of Thomsen-Friedenreich antigen on transitional cell cancer using monoclonal antibody

In 31 transitional cell cancer (TCC) tissues and 5 normal bladder mucosae (NBM), we compared the results of flow cytometry (FCM) and immunohistochemical examination in evaluating the expression of Thomsen-Friedenreich antigen (T-Ag) using a monoclonal antibody. On immunohistochemical examination, 14 (45%) cancer tissues showed T-Ag, while 7 (23%) cancer tissues and all NBM showed only cryptic T-Ag, which was detected only after neuraminidase treatment. Ten (32%) high grade cancer tissues showed neither T-Ag nor cryptic T-Ag. ON FCM the T-Ag positive cells (TPC) and the T-Ag positive cells after neuraminidase treatment (nTPC) were counted in fresh cell suspensions. FCM was more sensitive than immunohistochemical study in detecting T-Ag. Additionally, FCM revealed that some tumors had both T-Ag and cryptic T-Ag at the same time. The ratio of nTPC to TPC was well correlated with the stage or grade of the tumor and may be a more reliable marker of TCC than the expression of T-Ag assessed by immunohistochemical techniques.