Inhibition of phorbol ester-induced neutrophil chemiluminescence by FeLV

Hepatitis C virus core protein inhibits interleukin 12 and nitric oxide production from activated macrophages

A characteristic feature of hepatitis C virus (HCV) infection is a high frequency of persistence and the progression to chronic liver diseases. Recent data suggest that prevalent T helper (Th) 2 immunity as well as weak HCV-specific T-cell response is associated with viral persistence. Here, we showed that the production of interleukin 12 (IL-12) and nitric oxide (NO) that is critical for the induction of Th1 and innate immunity, but not that of tumor necrosis factor alpha (TNF-alpha), was significantly suppressed in both HCV core-expressing macrophage cell lines and mouse peritoneal macrophages treated with recombinant core protein. In addition, IL-12 p40 promoter activity was repressed by the presence of HCV core in macrophages stimulated with lipopolysaccharride (LPS) following IFN-gamma treatment, indicating that IL-12 production may be downregulated at the transcriptional level. We also found that proliferation of T cells and IFN-gamma production in mixed lymphocyte reactions (MLR) with core-expressing cells were inhibited. Taken together, our results suggest that HCV core protein could play roles in suppressing the induction of Th1 immunity through inhibition of IL-12 and NO production.

Loss of neutrophil and natural killer cell function following feline immunodeficiency virus infection

Experimental infection with the Mt. Airy isolate of feline immunodeficiency virus (FIVMA), a lentivirus isolated from a domestic cat exhibiting signs of an immunodeficiency-like syndrome, results in transient lymphadenopathy, fever, stomatitis, enteritis, neurologic abnormalities, and immunosuppression. The effects of FIVMA infection on neutrophil and natural killer cell (NK) function were examined in vitro. Suppression of neutrophil chemiluminescence (CL) responses, as well as reduction in NK-mediated cytotoxicity were demonstrated. Neutrophil CL was decreased by 50% in infected cats when compared to control values. This loss of CL was present through 6 months after infection. In addition, NK-mediated cytotoxicity was approximately 50% less in FIVMA infected cats than in controls. Loss of innate immunity was paralleled with inversion in feline CD4/CD8 lymphocyte ratios and decreases in lymphocyte mitogenesis seen as early as 5 weeks after infection. These results suggest that FIVMA infection induces an immunodeficiency disorder in infected cats similar to that seen in human immunodeficiency virus infections.

Photon emission of phagocytes in relation to stress and disease

Phagocytes, the first-line cells of the body's defence mechanisms against invading pathogens, kill microorganisms by means of lysosomal degradative enzymes and highly toxic reactive oxygen intermediates. The reactive oxygen compounds are produced, in a process called the 'respiratory burst', by the NADPH oxidase complex in plasma membranes, and by myeloperoxidase in phagolysosomes after degranulation. These processes generate electronically excited states which, on relaxation, emit photons, giving rise to phagocyte chemiluminescence (CL). This paper describes the conditions for the measurement of CL, and reviews the activity of phagocytes from individuals undergoing stress or disease. The capability of phagocytes to emit photons reflects remarkably well the pathophysiological state of the host. In many cases even the magnitude of the stress, the presence of a pathogen in the body, or the activity of the disease can be estimated. Physiological changes, e.g. in the reproductive cycle, can also be predicted.

Simultaneous separation and purification of mononuclear and polymorphonuclear cells from the peripheral blood of cats

Peripheral blood mononuclear cells (PBMC) and polymorphonuclear cells (PMNC) play important roles in immunodeficiency diseases and AIDS-like syndromes in cats caused by feline leukemia virus (FeLV) and presumably also when caused by feline immunodeficiency virus (FIV). For comparative or functional studies it is advantageous or necessary to obtain these cells as separate entities from the same sample of an animal. Therefore, we analyzed the technical parameters of obtaining, separating and purifying these cells simultaneously from several blood samples of several cats. Flow cytometric studies with outbred cats indicated that of various cell separation/purification methods, e.g. from lysed whole blood, by Histopaque 1.077 or 1.119 single-density, or by 1.077/1.119 double-density centrifugation, the 1.077/1.119 double-density centrifugation of diluted whole blood is the most consistent, practical and effective method of yielding both highly purified PBMC and PMNC as separate entities from the same sample. The interface between plasma and 1.077 contained an average 86% PBMC vs. 14% PMNC, and the interface between 1.077 and 1.119 an average of 2% PBMC vs. 98% PMNC. Lymphocytes separated by this method had an average CD4/CD8 T-cell ratio of 2.0. These data indicate that Histopaque 1.077/1.119 double-density gradient allows purification and physical separation of lymphocytes and phagocytes from a blood sample, enabling the investigator to examine both cell types from the same sample simultaneously.