Immunotherapy for cancer treatment.

BACKGROUND: Immunotherapy is an effective way to treat many diseases associated with disorders of the immune system by modulating immune response. It involves several ways of manipulating the immune system, which either suppress the immune response or, on the contrary, stimulates it. Immunotherapy is currently of immense importance not only in the context of the treatment of autoimmune diseases and immunodeficiencies, but it is also a promising method for treating cancer. Efforts to use the bodys own anti-tumor response have led to the discovery of alternative treatments for cancer. PURPOSE: The aim of this paper is to provide a literature review focused on the current possibilities of cancer immunotherapy. In addition to classical procedures such as chemotherapy and radiotherapy, treatments consisting of adoptive cell therapy and blockade of immune checkpoints are being increasingly indicated. The latest form of adoptive cell therapy is the use of T-lymphocytes expressing chimeric antigen receptors. This type of treatment is indicated for hematological cancers. In recent years, a new approach to the treatment of cancer has emerged using blockade of immune checkpoints by monoclonal antibodies. At present, antitumor therapy focuses on blocking of inhibitory molecules - cytotoxic T-lymfocyte antigen 4 (CTLA-4) and programmed cell death 1 (PD-1). Administration of anti-CTLA-4 receptor specific monoclonal antibodies blocks binding between CTLA-4 receptors and B7 ligands, thereby preventing inhibition of activated cytotoxic T cells. Another type of checkpoints of the immune response include PD-1 molecules expressed on the surface of T-lymphocytes, B-lymphocytes, but also on the surface of myeloid cells. Blockade of PD-1 receptors and PD-L1 ligands prevents the inhibition of T-lymphocytes by tumor cells, leading to an increase in the immune systems ability to recognize tumor cells and subsequently destroy them. Blockade of PD-1 receptors and PD-L1 ligands prevents the inhibition of T-lymphocytes by tumor cells, leading to an increased immune response to the recognition of tumor cells and their subsequent destruction. An alternative form of tumor treatment is the administration of tumor vaccines and tumor-specific monoclonal antibodies (mAbs). The use of mAbs to kill tumors requires the expression of tumor-specific antigens on the surface of tumor cells. Through these receptors, mAb targets cytotoxic cells, toxins, drugs, or radioisotopes to tumor cells and thereby destroys them. Also, mAbs are able to block angiogenesis, which is crucial in tumor cell proliferation.

Herpes simplex viruses type 1 and 2 photoinactivated in the presence of methylene blue transform human and mouse cells in vitro.

Three strains of herpes simplex virus, K17syn- and HSZPsyn+ of type 1 (HSV-1) and USsyn- of type 2 (HSV-2), were photoinactivated in the presence of methylene blue and used to infect 3 cell lines, normal human lung tissue cells (MRC-5), mouse epithelial cells (NIH3T3), and human lung carcinoma cells (A549). The virus titer and phenotype of cells were evaluated to compare the characteristics of normal and carcinoma cells infected with non-syncytial (non-syn) and syncytial (syn) strains of herpes simplex viruses. We found that the cells of both normal cell lines infected with photoinactivated K17syn- and USsyn- but not HSZPsyn+ acquired transformed phenotype accompanied by the presence of virus. Surprisingly, the infection with photoinactivated viruses K17syn- and USsyn- but not HSZPsyn+ resulted in the suppression of the transformed phenotype of A549 cells. Using nested PCR, herpesviral DNA was identified in newly transformed cells and cells that lost the transformed phenotype. The effect of putative herpesvirus-related growth factors (HRGF) produced by cells infected with photoinactivated viruses was quantified and compared. Since methylene blue is currently used in phototherapy of herpetic lesions, these results raise the question of whether such therapy is risky to human health.

Cells transformed by murine herpesvirus 68 (MHV-68) release compounds with transforming and transformed phenotype suppressing activity resembling growth factors.

In this study, we investigated the medium of three cell lines transformed with murine herpesvirus 68 (MHV-68) in vitro and in vivo, 68/HDF, 68/NIH3T3, and S11E, for the presence of compounds resembling growth factors of some herpesviruses which have displayed transforming and transformed phenotype suppressing activity in normal and tumor cells. When any of spent medium was added to cell culture we observed the onset of transformed phenotype in baby hamster kidney cells (BHK-21) cells and transformed phenotype suppressing activity in tumor human epithelial cells (HeLa). In media tested, we have identified the presence of putative growth factor related to MHV-68 (MHGF-68). Its bivalent properties have been blocked entirely by antisera against MHV-68 and two monoclonal antibodies against glycoprotein B (gB) of MHV-68 suggesting viral origin of MHGF-68. The results of initial efforts to separate MHGF-68 on FPLC Sephadex G15 column in the absence of salts revealed the loss of its transforming activity but transformed phenotype suppressing activity retained. On the other hand, the use of methanol-water mobile phase on RP-HPLC C18 column allowed separation of MHGF-68 to two compounds. Both separated fractions, had only the transforming activity to normal cells. Further experiments exploring the nature and the structure of hitherto unknown MHGF-68 are now in the progress to characterize its molecular and biological properties.

Recombinant herpesviruses as tools for the study of herpesvirus biology.

This article is a brief summary of efforts to generate mutant herpesviruses for investigating and assigning gene functions of herpesviruses in replication and pathogenesis. While a full review of all herpesviruses is beyond the scope of this review, we focused our attention on the prototype of the herpesvirus subfamily - herpes simplex virus and murine gammaherpesvirus that serves as an excellent animal model to study human gammaherpesvirus pathogenesis. Furthermore, our present knowledge of essential, non-essential, and common genes of herpesviruses as well as of accessory genes that are currently being studied with the help of the bacterial artificial chromosome (BAC) system will also be discussed. This system facilitates the analysis of herpesviral genes with potential for use in gene therapy or as anti-cancer therapeutics.

Sequence analysis of the regions flanking terminal repeats of the genome of umava isolate of murine gammaherpesvirus.

The umava isolate of murine gammaherpesvirus (MHV-umava) slightly differs from Murine gammaherpesvirus 68 (MHV-68) and two other isolates of murine gammaherpesvirus (MHV), MHV-76 and MHV-72 in some biological properties. To identify the region(s) in the MHV-umava genome responsible for this phenomenon, we compared the sequences flanking terminal repeats (TRs) of the MHV-umava genome with those of MHV-68, MHV-76 and MHV-72. Restriction and sequence analyses revealed in MHV-umava as compared to MHV-68 approximately 9.3 kbp deletion at the left end of the genome and approximately 1.5 kbp deletion at the right end of the genome. While the approximately 9.3 kbp deletion was similar to that in MHV-76, the approximately 1.5 kbp deletion was unique for MHV-umava.

Leukemia-like syndrome in Balb/c mice infected with the lymphotropic gamma herpesvirus MHV-Sumava: an analogy to EBV infection.

Based on our previous observation that primary infection with the murine gamma herpesvirus (MHV) isolate Sumava (MHV-SU) undergoes a lymphoproliferative phase resembling to Epstein-Barr virus (EBV) induced infectious mononucleosis (IM), we evaluated white blood cell (WBC) counts at late stages following MHV-SU infection. In consequence of intranasal inoculation with MHV-SU a leukemia-like syndrome in Balb/c mice developed. The syndrome in question was accompanied with significant splenomegaly; in the peripheral blood leukocytosis (from 8 x 10(4) to 5 x 10(5) leukocytes/microl) and a high percentage of atypical lymphocytes (60-80%) was found. Presented results are bringing further evidence for lymphoproliferative effect of MHV and point at analogic course of MHV-SU and EBV infections.