Natural killer cell activity assays

Several cytokines have been characterized at the molecular level in different species of marine mammals (Table 23.2). In addition, limited evidence exists for conserved functionality of cytokines in marine mammals, such as the ability of human recombinant IL-2 to stimulate T cell proliferation [32, 33] and natural killer cell activity [39,40] in beluga whales and harbor seals. Assays were developed to quantify circulating levels of cytokines [41,42], as well as C-reactive protein, a marker of acute inflammation [43],... 

Riccardi, C., Puccetti, P., Santoni, A. and Herberman, R.B. (1979). Rapid in vivo assay of mouse natural killer cell activity. J. Natl. Cancer Inst. 63 1041-1045. 

Blom WMW, van Nielen WGLW, de Groene EME, Albers RR (2009) A cell-based screening assay for Natural Killer cell activity. Int Immunopharmacol 9 746-752... 

Johann S, Bltlmel G, Lipp M, Forster R. A versatile flow-cytometry-based assay for the determination of short- and long-term natural killer cell activity. J Immunol Methods 1995 185 209-216. 

Blomberg, K., Granberg, C., Hemmila, I., and Lbvgren, T. (1986) Europium-labelled target cells in an assay of natural killer cell activity. I. A novel non-radioactive method based on time-resolved fluorescence. J. Immunol. Meth. 86 225-229. 

The most relevant bioassays measure specific activities on immune function, either as effector or regulatory, for example, assay of cytokine IL-12 by the augmentation of the cytolytic function of natural killer cells (B9), IL-10 by the inhibition of the production of TNF-o from stimulated monocytes (B13), and IL-8 and eotaxin by the chemotaxis of neutrophils and eosinophils, respectively (C2). 

In vitro assays of activity of natural killer cells Mitogenic stimulation assay of B- and T-lymphocytes Macrophage activity assays Stem cell assays... 

The various organs of the immune system such as spleen, lymph nodes, thymus and bone marrow containing the cells involved in the various immune responses offer the possibility to harvest these cells and perform in vitro assays for evaluation of effects on the immune system. When part of an in vivo animal study this may indicate a direct toxic effect of pharmaceuticals, that is, immunosuppression (Table 18.2). So, it is feasible to obtain cell suspensions for further evaluation such as determination of cellular subsets of T and B leukocytes by fluorescent activated cell sorter analysis (FACS analysis), and determination of natural killer (NK) cell activity of the spleen cell population. An advantage of this approach is that it may lead to identification of a biomarker to be used in clinical studies. In addition, in vitro stimulation of spleen cells with mitogens activating specific subsets may indicate potential effects on the functionality of splenic cell populations. Concanavalin A (Con A) and phytohemagglutinin (PHA) activate Tcells, while lipopolysaccharide (LPS) activates primarily B cell populations. Blood is collected for total white blood cell (WBC) determination and blood cell differential count. In addition, serum can be obtained for determination of serum immunoglobulins. 

Data from KLH-vaccinated cynomolgus monkey infants show an evident TDAR in animals of 3 months of age and a pronunced secondary antibody response to a booster immunization approximately 3 months thereafter (Figure 18.2). Since TDAR requires functional antigen-presenting cells, T cells, and B cells (including the switch to antibody-producing plasma cells), it is supposed to be the most relevant functional assay for a general assessment of immunosuppression. Besides others, another functional assay to be considered for use in juvenile monkeys is a functional test of natural killer (NK) cell activity. 

Morales A, Ottenhof PC (1983) Clinical application of a whole blood assay for human natural killer (NK) cell activity. Cancer 52 667-670... 

K. (1995) Time-resolved fluorometric assay for natural killer activity using target cells labelled with a fluorescence enhancing ligand. In press. 

Natural killer (NK) cells are a subpopulation of lymphocytes that can lyse a wide variety of tumor cells and some normal cells. They are classified as null cells, being neither B or T cells. The assay usually is an in vitro one in which target cells, labeled with 51Cr are exposed to the NK cell population, and the amount of radioactive 51Cr released is measured. NK cell activity is highest in young animals (mice 5-8 weeks of age), and is present in very low levels, if at all, in older animals. However, when older rats were exposed to C. parvum or BCG, there was an increase in the cytotoxicity of the lymphocyte population. 

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