Philippe Hainaut

Transfection and expression of a gene coding for a human melanoma antigen recognized by autologous cytolytic T lymphocytes

Human melanoma line MZ2-MEL expresses several antigens recognized by autologous cytolytic T lymphocytes (CTL). As a first step towards the cloning of the gene coding for one of these antigens, we tried to obtain transfectants expressing the antigen. The DNA recipient cell was a variant of MZ2-MEL which had been selected with a CTL clone for the loss of antigen E. It was cotransfected with genomic DNA of the original melanoma line and with selective plasmid pSVtkneoβ. Geneticin-resistant transfectants were obtained at a frequency of 2 × 10−4. These transfectants were then screened for their ability to stimulate the production of tumor necrosis factor by the anti-E CTL clone. One transfectant expressing antigen E was identified among 70 000 drug-resistant transfectants. Its sensitivity to lysis by the anti-E CTL was equal to that of the original melanoma cell line. When this transfectant was submitted to immunoselection with the anti-E CTL clone, the resulting antigen-loss variants were found to have lost several of the transfected pSVtkneoβ sequences. This indicated that the gene coding for the antigen had been integrated in the vicinity of pSVtkneoβ sequences, as expected for cotransfected DNA.

Pulmonary embolism findings on chest radiographs and multislice spiral CT

Multislice spiral CT is becoming an increasingly important tool for diagnosing pulmonary embolism. However, in many instances, a chest radiograph is usually performed as a first-line examination. Many parenchymal, vascular, and other ancillary findings may be observed on both imaging modalities with a highly detailed depiction of abnormalities on multislice CT. A comprehensive review of chest radiograph findings is presented with side-by-side correlations of CT images reformatted mainly in the frontal plane.

Genes Coding for TUM- Transplantation Antigens. A Model for TSTA?

It has been known for a long time that some experimental tumors express antigens that constitute targets for immune rejection by the syngencic host. The existence of these tumor-specific transplantation antigens (TSTA) was first demonstrated with chemically induced mouse sarcomas: each independent tumor was found to express a different antigen (Prchn 1957). Later, these findings were extended to ultraviolet-induced tumors (Kripke 1981). The generality of the existence of transplantation antigens specific for each tumor was however put under serious question when spontaneous mouse tumors were found to be completely incapable of eliciting an immune rejection response (Hewitt 1976). But further, experiments demonstrated that even these tumors express weak TSTA that arc potential targets for immune rejection (Van Pel 1983).

ACUTE RENAL FAILURE DUE TO DIFFUSE EXTRAMEDULLARY PLASMOCYTOMA

A 75-year-old woman with a history of multiple myeloma was admitted because of recent onset of vomiting, nausea and weakness. On admission, renal function was severely impaired, with serum creatinine level peaking at 26.8 mg per decilitre (normal value: 0.6-1.5 mg). Despite ongoing treatment by thalidomide, the IgG kappa monoclonal protein had sharply increased over the last few months, underlying the progression of haematological malignancy. A nonenhanced abdominal computed tomography (CT) displayed bilateral uretero-hydronephrosis due to compression by large retroperitoneal masses and a moderate accumulation of ascites (Figure 1). FDG-PET imaging performed 6 months earlier already demonstrated enhanced metabolic activity of subcutaneous and retroperitoneal masses (Figure 2). Pathological examination of both masses and peritoneal fluid revealed massive infiltration by abnormal plasma cells exhibiting kappa light chain restriction. The insertion of bilateral nephrostomy allowed to normalize renal function. Bortezomib and dexamethasone were administered. Extramedullary plasmocytoma composed of monoclonal plasmacytic cells,

Identification of Point Mutations in Genes Coding for tum-Antigens. A Step Towards the Understanding of Mouse and Human Tumor-Specific Transplantation Antigens?

Most experimental tumors induced with chemical carcinogens or UV radiation express individually specific transplantation antigens that elicit a T cell-mediated immune rejection in the syngeneic animals (Prehn and Main 1957; Klein et al. 1960; Kripke 1981; Uyttenhove et al. 1983). The characterization of these transplantation antigens has proved very difficult and several different approaches have been followed. One involves the search for specific antibodies to isolate the antigen by immunoprecipitation. Unfortunately, tumors seldom elicit antibodies directed against their specific transplantation antigens. One notable exception is UV-induced tumor 1591, and the molecules that were isolated with these antibodies proved to be modified H-2 class I molecules (Phillips et al. 1985; Linsk et al. 1986). Another approach involves the biochemical fractionation of membrane constituents and the assay of their ability to induce in vivo a specific immune protection against the tumor. It was applied to methylcholanthrene-induced sarcomas and a family of 96-kDa surface glyco-proteins was recently reported to induce a specific immunity (Srivastava et al. 1987). We have used yet another approach aimed at the direct isolation of genes coding for “tum-” transplantation antigens, which are observed on mouse tumor cells treated with mutagens. We begin therefore with a brief description of this system.