SUMMARYOrnithine decarboxylase (ODC), a regulatory enzyme of polyamine biosynthesis, is involved in cell growth and differentiation. Lack of information about the exact cellular and subcellular localization of ODC is one of the main obstacles to precise interpretation of the biological roles of the ODC/polyamine system. Here we describe the development and optimization of an immunocytochemical method to detect ODC in cells and tissues. For this purpose a monoclonal antibody (MP16-2) against a defined epitope of ODC protein was developed. Specificity of the antibody for ODC was substantiated by Western blotting and ELISA analysis using cell and tissue homogenates. In cultured cells, optimal staining results were obtained after fixation with crosslinking fixatives followed by permeabilization with methanol. In rat tissues, ODC immunoreactivity was best preserved in paraffin sections fixed with Bouin's fixative. Antigen retrieval using SDS and citrate buffer substantially increased ODC immunostaining and decreased background staining. Localization studies of ODC in different cell lines showed that strongest staining for ODC was found in the nucleoplasm of mitotic cells, whereas confluent cells showed moderate perinuclear staining. Immunocytochemical studies of various rat tissues showed high cytoplasmic immunostaining of ODC in epithelial cells of kidney, prostate, and adrenal medulla of testosterone-treated rats, in glandular epithelium of small intestine, and in pancreas of neonatal and adult rats.
Pretreatment with a low dose of recombinant human interleukin-1 (IL-1) (3 to 30 g/kg) 24 h before a lethal Pseudomonas aeruginosa infection prolongs survival in neutropenic mice. We investigated the role of the type I IL-1 receptor (IL-1RI) and IL-1RII in this IL-1-induced protection by using a specific IL-1 receptor antagonist (IL-1-Ra), which blocks effects mainly via IL-1RI. Pretreatment with IL-1Ra before IL-1 partially blocked the IL-1-induced enhanced survival, whereas pretreatment with a specific neutralizing monoclonal antibody to IL-1RI (35F5) eliminated the IL-1 induced protection. The nonapeptide fragment 163-171 of recombinant human IL-1, which possesses the immunoadjuvant but not the inflammatory effect of the entire molecule via a non-receptor-mediated signal transduction process, did not reproduce the IL-1-induced protection. IL-1-induced protection was associated with reduced serum aspartate aminotransferase and alanine aminotransferase concentrations in conjunction with ameliorated histopathology of the liver. These findings may be due to reduced cytokine production and cytokine sensitivity of target cells after infection. We conclude that the IL-1-induced nonspecific resistance to infection is mediated by cells bearing IL-1RI and is associated with a reduction of liver damage.
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