Expression of the chimeric IgE gene in cell culture and in various mouse tissues

Endoglin is Highly Expressed in Human Mast Cells

Endoglin, known to be expressed in proliferating vessels, is of worth when evaluating microvessel density as a prognostic factor in many types of malignancies, including some subtypes of leukemia cells. In childhood acute lymphoblastic leukemia, endoglin is associated with adverse outcome. In bone marrow, endoglin identifies the repopulating hematopoietic stem cells. Mast cells are a component of normal tissue and play an important role in the regulation of several processes, including inflammation and neoplasia. The aim of this study was to evaluate the use of endoglin as a biological marker of mast cells compared with the gold standard stains. We studied 15 specimens of neurofibroma, 9 of mastocytosis, and 6 of fibrous scar tissue through immunohistochemistry (for endoglin and mast cell tryptase) and histochemical staining using toluidine blue. Quantitative analysis of the cells was performed by counting 5 hotspots. The validity of endoglin as a mast cell marker was assessed by intraclass correlation coefficient. The Kruskal-Wallis test was used to compare mast cell count for each marker. A strong endoglin expression was found in the cytoplasmic granules of mast cells within the 3 groups. Similar results were observed with mast cell tryptase as well as toluidine blue. The intraclass correlation coefficient revealed that endoglin is a highly reliable biomarker of mast cells when compared with mast cell tryptase and toluidine blue. In conclusion, endoglin may assist in the diagnosis and pathogenesis study of various processes associated with mast cells. An endoglin-neutralizing treatment for solid cancers and leukemia could also affect mastocytes and the immunologic system.

[Antibody engineering: barnase-barstar module as a molecular constructor]

Today, antibody engineering for clinical applications is a rapidly progressing field of science and a big business. The basic functions of an antibody can be spatially differentiated and attributed to various structural domains of a molecule. Therefore, each of them may be an object for engineering with the aim of using a definite antibody function. In this sense, the potential of antibodies is unique. In this article, recent achievements and current problems of antibody engineering are briefly reviewed. The main attention is focused on a molecular constructor that allows for obtaining, with the help of a versatile barnase-barstar module, mono- and multiva-lent miniantibodies and their derivatives with outlined properties.

Expression of anti-tumor recombinant IgG- and IgE-like genes in eukaryotic cells

The tandem of humanized variable VL and VH genes (ScFv fragment 4D5) possessing a high affinity to the HER-2/neu oncogene (the epidermal growth factor receptor expressed in many types of human tumors) was attached through a flexible linker to the second exon of human antibodies of IgG or IgE isotypes constant gene. The humanized construct of IgE isotype was generated for the first time. Genes of the recombinant antibodies were cloned into the pCl-neo vector under the control of universal cytomegalovirus (CMV) promoter. Transfected HEK-293 cells efficiently produced antibodies of the corresponding isotypes IgE and IgG1. The results of Western blotting confirmed homogeneity of the expressed antibodies, which had the predicted molecular weight and specifically interacted with the HER-2/neu. The attachment of leader peptide to the 5'-end of the gene resulted in the preferential accumulation of recombinant antibodies in the cultural medium. These results indicate that de novo constructed humanized immunoglobulin genes express functionally active, single-chain recombinant antibodies in eukaryotic cells.

Eukaryotic expression vectors and immunoconjugates for cancer therapy

This review considers ways to address specificity to therapeutic targeted anticancer agents. These include transcriptional activation of tissue- and tumor-specific promoters in eukaryotic expression vectors and use of antitumor-directed immunoconjugates. The review deals with analysis of strategies used for selection of targeted promoters and examples of antibody fusion proteins exhibiting antitumor activity. A new direction in antitumor treatment pooling together methods of gene therapy and antibody therapy has appeared. This direction is based on the development of vectors encoding secreted forms of immunoconjugates. After vector introduction into a cell, the latter is capable of synthesizing and secreting antibody fusion protein composed of a therapeutic anticancer agent and antibody specifically targeted to cancer cells.