Accurate and rapid assessment of MHC antigen upregulation following cytokine stimulation

A new highly specific monoclonal antibody against placental alkaline phosphatase: a potential marker for the early detection of testis tumour

OBJECTIVE

To develop specific monoclonal antibodies (mAbs) against human germ cell tumours.

MATERIALS AND METHODS

A single-cell suspension obtained from tumour tissue fragments (consisting of both tumour and normal compartments) from a patient with seminoma was used as an immunogen. Spleen cells from immunized mice were used to develop mAbs. Tissue specificity, biochemical characteristics and competitive studies were analysed using immunocytochemical staining, dot blots and a Western blot analysis, to identify target antigen(s).

RESULTS

The immunization protocol led to the development of 107 hybridomas, 90 of which were negative against the original tissue biopsies. The remaining 17 showed positivity against various tissue compartments. One selected mAb (ATC2) showed specific staining on germ cell tumours but not on normal tissues, and positive staining with some human tumour cell lines. The target antigen for ATC2 was confirmed to be placental alkaline phosphatase (PLAP) based on: Western blot analysis compared with commercially available PLAP; comparison of the data with another well-known anti-PLAP mAb (H17E2, although the two mAbs recognized different antigenic epitopes); heat resistance characteristics; high-performance liquid chromatography of the ATC2 target antigen and purified PLAP.

CONCLUSION

The selected mAb ATC2 has high specificity for human germ cell tumours, the target antigen for ATC2 being PLAP, although the antigenic epitope(s) differ from those recognized by H17E2. Thus ATC2 may be useful for monitoring serum levels of PLAP in patients with testis cancer and may be relevant for detecting cancer cells in the semen of individuals with suspected testis cancer, particularly in those with equivocal findings on ultrasonography.

Coxsackie and adenovirus receptor (CAR)-dependent and major histocompatibility complex (MHC) class I-independent uptake of recombinant adenoviruses into human tumour cells

The role of two receptors, previously proposed to mediate the entry of adenoviruses into human cells, the coxsackie and adenovirus receptor (CAR) and the major histocompatibility complex (MHC) class I heavy chain has been investigated. The expression of MHC class I in many tumours is reduced or absent, therefore if this were a means by which adenoviruses gained entry into cells, it would have important implications for their application in cancer treatment. In order to determine if MHC class I heavy chain is involved in adenovirus type 5 (Ad5) uptake, the binding of recombinant Ad5 fibre knob domain (which mediates viral attachment) to human cell lines that had greatly different levels of surface MHC class I was studied. We also created derivatives of a non-permissive Chinese hamster ovary (CHO) cell line that expressed human class I (HLA-A2) and found that these cells did not bind fibre or take up virus. In addition, the extracellular domain of CAR was expressed in E. coli and used to generate a polyclonal anti-CAR antibody. This antibody blocked both 125I labelled fibre knob binding and virus uptake. Thus CAR, and not MHC class I, is a receptor for human adenoviruses in cultured tumour cells. Tissue CAR levels may therefore be an important factor in the efficiency of adenovirus-mediated gene therapy.

Presence of an eosinophilic infiltrate in cervical squamous carcinoma results from a type 2 immune response

OBJECTIVES

The presence of an eosinophilic infiltrate in patients with cervical squamous carcinoma has been shown to correlate with a worse overall survival, suggesting a less effective immune response in these cases. Since type 2 cytokines such as IL-4 and IL-5 are known to attract eosinophilic granulocytes, an immunohistochemical study was performed to gain further insight as to whether a type 1 or type 2 immune response is involved in eliciting an eosinophilic infiltrate.

MATERIAL AND METHODS

Frozen tissue sections of 9 normal cervical tissues, 23 premalignant cervical lesions, and 23 cervical squamous carcinomas were stained by immunohistochemistry with monoclonal antibodies directed against IFN-gamma and IL-4 as representatives of a type 1 or a type 2 response, respectively.

RESULTS

Normal tissues and premalignant lesions of the cervix did not contain eosinophilic granulocytes and showed very few IL-4- and IFN-gamma-positive cells. In cervical carcinoma the presence of IL-4 on tumor infiltrating cells correlated with the presence of eosinophilic granulocytes in the tumor (P value <0.01) and stroma (P value <0.05). IFN-gamma-positive cells did not show any such correlation. In addition, colocalization was observed of CD3- and IL-4-positive T lymphocytes indicating that IL-4 production is mediated by T lymphocytes.

CONCLUSION

The relative increase of IL-4-positive cells in the presence of an eosinophilic infiltrate might thus reflect an imbalance between a type 1 and type 2 response, in favor of the latter. Since a type 1 response stimulates an adequate cellular response which is negatively regulated by type 2 cytokines, these findings might explain the worse clinical outcome seen in cervical cancer patients with an eosinophilic tumor infiltrate. These results may have implications when developing immunotherapeutical strategies for cervical cancer.

Immunotherapeutic strategies for cervical squamous carcinoma

Progress in developing preventive and therapeutic vaccines for HPV-associated diseases has been made in the last few years, but continued studies are needed to evaluate the clinical feasibility of different vaccination approaches and to determine a clinically effective and safe one. The perfect HPV vaccine will have both preventive and therapeutic capabilities, and because it is likely to be used world-wide, especially in developing countries, it must also have low production costs.