Generation of antibodies to the urokinase receptor (uPAR) by DNA immunization of uPAR knockout mice: membrane-bound uPAR is not required for an antibody response

Biochemical and immunological characterization of a novel monoclonal antibody against mouse leukotriene B4 receptor 1

Leukotriene B₄ (LTB₄) receptor 1 (BLT1) is a G protein-coupled receptor expressed in various leukocyte subsets; however, the precise expression of mouse BLT1 (mBLT1) has not been reported because a mBLT1 monoclonal antibody (mAb) has not been available. In this study, we present the successful establishment of a hybridoma cell line (clone 7A8) that produces a high-affinity mAb for mBLT1 by direct immunization of BLT1-deficient mice with mBLT1-overexpressing cells. The specificity of clone 7A8 was confirmed using mBLT1-overexpressing cells and mouse peripheral blood leukocytes that endogenously express BLT1. Clone 7A8 did not cross-react with human BLT1 or other G protein-coupled receptors, including human chemokine (C-X-C motif) receptor 4. The 7A8 mAb binds to the second extracellular loop of mBLT1 and did not affect LTB₄ binding or intracellular calcium mobilization by LTB₄. The 7A8 mAb positively stained Gr-1-positive granulocytes, CD11b-positive granulocytes/monocytes, F4/80-positive monocytes, CCR2-high and CCR2-low monocyte subsets in the peripheral blood and a CD4-positive T cell subset, Th1 cells differentiated in vitro from naïve CD4-positive T cells. This mAb was able to detect Gr-1-positive granulocytes and monocytes in the spleens of naïve mice by immunohistochemistry. Finally, intraperitoneal administration of 7A8 mAb depleted granulocytes and monocytes in the peripheral blood. We have therefore succeeded in generating a high-affinity anti-mBLT1 mAb that is useful for analyzing mBLT1 expression in vitro and in vivo.

Organization, evolution and functions of the human and mouse Ly6/uPAR family genes

Members of the lymphocyte antigen-6 (Ly6)/urokinase-type plasminogen activator receptor (uPAR) superfamily of proteins are cysteine-rich proteins characterized by a distinct disulfide bridge pattern that creates the three-finger Ly6/uPAR (LU) domain. Although the Ly6/uPAR family proteins share a common structure, their expression patterns and functions vary. To date, 35 human and 61 mouse Ly6/uPAR family members have been identified. Based on their subcellular localization, these proteins are further classified as GPI-anchored on the cell membrane, or secreted. The genes encoding Ly6/uPAR family proteins are conserved across different species and are clustered in syntenic regions on human chromosomes 8, 19, 6 and 11, and mouse Chromosomes 15, 7, 17, and 9, respectively. Here, we review the human and mouse Ly6/uPAR family gene and protein structure and genomic organization, expression, functions, and evolution, and introduce new names for novel family members.

Discovery and immunologic validation of new antigens for therapeutic cancer vaccines

Immunotherapy using both active and passive approaches is increasingly being used as a modality to treat human cancer. The last decade has seen a tremendous burst of activity in antigen discovery in cancer, and many new targets have now been identified for both monoclonal antibody therapy and active immunization. In addition, advances have been made in our understanding of the immune response against cancer and how new vaccine vectors, such as poxviruses, alphaviruses and bacterial vectors, can be used to overcome some of the traditional hurdles (e.g. self-tolerance and immune suppression in cancer patients) that have hindered the generation of effective antitumor immune responses. Improvements in genomics technology in the area of DNA microarrays and differential display and subtractive hybridization together with a new wave of mass spectrometry-based proteomics tools, as well as more sensitive assays to validate the immunoreactivity of new antigens, have all accelerated the rate of new antigen discovery in cancer. This rapid progress should initiate a major paradigm shift in how we treat cancer within the next 10 years, where, instead of being a novelty, the combination of targeted T cell-based vaccines and antiangiogenesis therapies will be routinely combined with traditional chemotherapy. The successful combination of these approaches will change the face of cancer from a relatively acute, life-threatening disease to a manageable chronic disorder with long survival times.