Treatment of tumor cells with interferon-gamma (IFN) frequently reduces their susceptibility towards NK cells and results in augmented expression of MHC antigens, which may increase immunogenicity of tumor cells. Depending on the relative strength of these opposing effects, i.e. escape from non-adaptive immune defense versus facilitated activation of T-cell-mediated defense, IFN-treatment may be beneficial or disadvantageous for the tumor-bearing host. This is demonstrated for the variants F1 and F10 of the B16 melanoma, which differ in metastasizing capacity. IFN-treatment of B16-F1 melanoma cells significantly reduced susceptibility towards non-adaptive immune defense, and increased metastasizing potential. On the other hand, H2K antigen expression was augmented by a factor of 50; concomitantly, lysability by CTL was increased, together with the number and expansion rate of cytotoxic T-cell precursors (CTLp) recruited after immunization with IFN-treated B16-F1. The benefit of increased antigenicity and immunogenicity outweighed the disadvantage or reduced susceptibility towards non-adaptive immune defense. B16-F10 cells were less susceptible to NK cells, expression of MHC antigens was found to be stronger and they were more immunogenic than B16-F1 cells. After IFN-treatment, susceptibility to non-adaptive immune defense was further reduced. Expression of MHC antigens as well as antigenicity and immunogenicity were only moderately augmented. As a consequence, the decreased susceptibility to non-adaptive immune defense was dominating in the tumor bearing host and could not be counterbalanced by immunization with IFN-treated B16-F10 cells. We interpret these data to show that a precise knowledge of the relative decrease in susceptibility to non-adaptive immune defense, the relative increase in MHC antigen expression, antigenicity and immunogenicity may allow a more precise prognosis of the influence of IFN on metastatic capacity in the B16 system, and eventually also in a clinical therapeutic regimen.

Animals↗

PubMedDate not supplied

Changes in adhesive properties of tumor cells do not necessarily influence metastasizing capacity.

BSp6S and BSp73AS are two rat tumors which grow locally after intra-footpad (ifp) application. BSp73ASML and BSp6AS are variants, which metastasize via the lymphatics. Both variants have lost adherence properties, as shown by in vitro culture on plastic surfaces, suggesting that loss of adherence may be accompanied by increased metastasizing capacity. However, after growth of BSp6S and BSp73AS in vitro on poly(2-hydroxyethylmethacrylate) (polyHEMA)-coated plates, which resulted in loss of adherence and spreading, and subsequent intravenous (iv) or ifp injection of non-adherent tumor cells into syngeneic rats, metastasizing capacity was not increased. It is concluded that loss of adherence may facilitate metastatic spread, but certainly is not sufficient for initiation.

Animals↗

PubMedDate not supplied

Identification of renal-cell-carcinoma-related cDNA clones by suppression subtractive hybridization.

The identification of human genes expressed exclusively or preferentially in tumour tissue will be of interest for exploiting the process of oncogenesis, for diagnostic purposes and possibly for developing new strategies in cancer immunotherapy. In an attempt to identify genes differentially expressed in renal cell carcinoma we used the method of suppression subtractive hybridization, comparing renal cell carcinoma tissue with non-transformed kidney tissue. From randomly selected clones, nine were identified to be differentially expressed in renal cell carcinoma. Sequence analysis of seven out of the nine revealed substantial homologies with known genes, the remaining two cDNA clones did not match with any sequences in the GenBank/EMBL database, indicating that they may be novel genes. Notably, expression of five out of the seven known genes is associated with the malignant phenotype. Thus, suppression subtractive hybridization is an effective technique of high sensitivity for the detection of differentially expressed transcripts, not only in cell lines but also for tumour tissue.

Blotting, Northern↗

PubMedDate not supplied

In vivo manipulation of interleukin-2 expression by a retroviral tetracycline (tet)-regulated system.

We have used the tetracycline (tet)-regulated system as described previously to evaluate the applicability of controlled gene expression in cancer gene therapy. As a model gene, we used the human interleukin-2 (IL-2) gene, which has been placed under the transcriptional control of the tetO/promoter. Human melanoma cells were transduced by two modified retroviral tet vectors containing the transactivator regulatory unit and the IL-2 gene driven by the tetO/promoter, respectively. In the absence of tet, IL-2 expression in the target cells was stable over several months. IL-2 production was in the range of 40 U/10(6) cells/24 hours. A fine tuning of IL-2 expression could be achieved by culturing the transduced cells with increasing doses of tet, whereby a concentration of 500 ng/mL tet in the culture medium abrogated IL-2 expression. Most importantly for clinical application, IL-2 expression by the transduced melanoma cells could also be regulated in vivo. When nu/nu mice were inoculated with the transduced tumor cells, they failed to develop tumors. Instead, the inhibition of IL-2 expression in the transduced tumor cells by oral administration of tet led to subcutaneous tumor growth; this growth rate was comparable with the growth rate of subcutaneously inoculated untransduced parental cells. The finding demonstrates the applicability of the tet-regulated system in cancer gene therapy.

3T3 Cells↗

PubMedDate not supplied

Heart rhythm in patients with neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1) is a common inherited disorder. Neurofibromas may be situated almost anywhere in the body, including mediastinum, myocardium and autonomic nervous system. We, therefore, tested our hypothesis that arrhythmias would be more common during a 24-hour period in patients with NF1 than in control subjects. In a follow-up study of NF1 patients in Gothenburg, 38 out of 47 NF1 patients entered a study for comparison with 41 controls. We did not find any excess of arrhythmias. There were, however, fewer cases with episodes of bradycardia among the NF1 patients (p < 0.01) than among the controls. This might be explained by vagus nerve involvement.

Adult↗

PubMedDate not supplied

Costimulatory molecules and their ligands as therapeutic targets in autoimmune disease.

The initiation and progression of autoimmune diseases are complex processes that depend on a selective breakdown of tolerance and additional factors like genetic susceptibility and environmental factors, e.g. drugs, infections, toxins and UV light. The causative failure of the immune system to tolerate self can be initiated by molecular mimicry or polyclonal activation with the consequence of a breakdown of anergy or a failure of activation induced cell death. It presents itself in multiple forms including a disturbed balance between TH1 and TH2, alterations in the cytokine milieu and undue modulation of the expression of costimulatory molecules. Although all these features may vary between patients and within the individual patient depending on the state of disease, recent years have provided convincing evidence that, in particular, disease progression is markedly influenced by the expression profile of costimulatory molecules. Since in many forms of autoimmune diseases the causative self-antigen(s) are unknown, therapy largely depends on anti-inflammatory agents or in severe cases on a general immunosuppression. Increasing knowledge of the functional activities of costimulatory molecules in autoimmune disease now provides a new and promising therapeutic modality, which in a more selective way interferes with the pathological activities of immune cells. Here I discuss evidence for the involvement of costimulatory molecules, particularly of CD44 variant isoforms, in autoimmune diseases and their possible use as a therapeutic target. Due to the regulated and restricted expression of these molecules, treatment should not be burdened by severe side effects.

Autoimmune Diseases↗