An improved method to quantitate phagocytosis with mineral oil particles which avoid cell flotation

Immunoprotective activity of a Salmonid Alphavirus Vaccine: comparison of the immune responses induced by inactivated whole virus antigen formulations based on CpG class B oligonucleotides and poly I:C alone or combined with an oil adjuvant

CpG oligonucleotides and polyinosinic:polycytidylic acid (poly I:C) are toll-like receptor (TLR) agonists that mimic the immunostimulatory properties of bacterial DNA and double-stranded viral RNA respectively, and which have exhibited potential to serve as vaccine adjuvants in previous experiments. Here, a combination of CpGs and poly I:C together with water- or oil-formulated Salmonid Alphavirus (SAV) antigen preparations has been used for a vaccine in Atlantic salmon and tested for protection in SAV challenge trial. The results demonstrate that vaccination with a high dose of the SAV antigen induced protection against challenge with SAV which correlated with production of neutralizing antibodies (NAbs). As the high antigen dose alone induced full protection, no beneficial effect from the addition of CpG and poly I:C could be observed. Nevertheless, these TLR ligands significantly enhanced the levels of NAbs in serum of vaccinated fish. Interestingly, gene expression analysis demonstrated that while addition of oil suppressed the CpG/poly I:C-induced expression of IFN-γ, the upregulation of IFNa1 was substantially enhanced. A low dose of the SAV antigen combined with oil did not induce any detectable levels of NAbs either with or without TLR ligands present, however the addition of CpG and poly I:C to the low SAV antigen dose formulation significantly enhanced the protection against SAV suggesting that CpG/poly I:C may have enhanced a cytotoxic response - a process which is dependent on the up-regulation of type I IFN. These results highlight the immunostimulatory properties of the tested TLR ligands and will serve as a ground for further, more detailed studies aimed to investigate their capacity to serve as adjuvants in vaccine formulations for Atlantic salmon.

A human cell system for detecting asbestos cytogenotoxicity in vitro

Crocidolite, a carcinogenic asbestos in humans, specifically induces mesothelioma. We investigated the cytogenotoxic effects of crocidolite in a human mesothelioma cell line, MSTO211H, and a human promyelocytic leukemia cell line, HL60. Using confocal laser scanning microscopy, we found that the MSTO211H cells had phagocytotic activity, whereas the HL60 cells did not. In the MSTO211H cells, crocidolite decreased the cell population and increased the numbers of polynucleated cells (PN) and tetraploid cells, and increased the coefficients of variation (CV) of DNA contents in G0/G1 cells and the formation of 8-hydroxydeoxyguanosine. In contrast, crocidolite showed none of these cytogenotoxic effects in HL60 cells. To investigate the importance of phagocytosis in the cytogenotoxicity of crocidolite, we sorted the crocidolite-phagocytosed cells from less-phagocytosed cells by fluorescence-activated cell sorting, and studied the differences in cytogenotoxicity between these two cell groups. We found significant increases in the numbers of PN and tetraploid cells and the CV in the crocidolite-phagocytosed cells compared to the less-phagocytosed cells. These findings indicate that MSTO211H cells are susceptible to the cytogenotoxic effects of asbestos due to their phagocytotic activity, and that the MSTO211H cell line is suitable for the detection of such effects on human cells by asbestos and other materials which need to be phagocytosed to exert their toxicity.

Phagocytosis, intracellular pH, and cell volume in the multifunctional analysis of granulocytes by flow cytometry

Phagocytosis of Escherichia coli K12 strain bacteria was used to measure by flow cytometry the functional activities of human granulocytes in whole blood or buffy coat preparations. In a first measurement, the increase in electric cell volume and acridine orange (AO) green and red fluorescence were used to quantify the degree of phagocytosis. In a second measurement, the intracellular pH and esterase activity of each cell were determined with 1,4-diacetoxy-2,3-dicyanobenzene to obtain information on the metabolic activities during phagocytosis and degradation of bacteria. The DNA of dead cells was simultaneously counterstained with propidium iodide in both assays. The volume, the AO green and red fluorescence, the internal pH, and esterase activity were automatically averaged for all granulocytes or lymphocytes of a measurement. The calculated mean values were transferred into the self-learning database of the DIAGNOS1-program system. The functional granulocyte parameters of normal healthy individuals can be used as reference values for the automated diagnosis of abnormal granulocytes in various infectious disease states. The assays require 1 ml of heparinized whole blood and the results are available within 1 hour.

Modulation of human neutrophil function by C-reactive protein

Investigation of the effect of C-reactive protein (CRP), an acute-phase reactant, on the functional capacities of human neutrophils was carried out as the basis for elucidating the biological function of C-reactive protein. An initial stimulation at low concentrations, followed by inhibition of superoxide production, and secretion of vitamin-B12-binding protein in the presence of two stimulants, phorbol myristate acetate and concanavalin A, and of neutrophil chemotaxis with increasing concentration of CRP was observed. Correlation between modulation of cell function, at least at relatively high CRP concentrations (greater than 50 micrograms/ml) and an increase in the intracellular level of cAMP is suggested. CRP was also found to enhance neutrophil phagocytosis of particles not containing phosphorylcholine, the native CRP ligand. The proposed role of CRP in neutrophil function is one of regulation and as a negative feedback for potential cytotoxic neutrophil functions.