Biomedical subjects

P Britton

Publications and source records attributed to P Britton.

92 records · Page 6Linked to original sources

PubMedDate not supplied

Specific cytotoxic lymphocyte response in swine against structural proteins of transmissible gastro-enteritis virus: a study using lymphoblastoid cell line and recombinant vaccinia virus.

To determine the specificity, if any, of cellular cytotoxicity against transmissible gastro-enteritis virus (TGEV) infected cells, we developed a test using B lymphoblasts from a MHC histocompatible (d/d haplotype) cell line (L14), as stimulating and target cells. These cells were previously infected with recombinant vaccinia virus including different TGEV structural genes, either the spike (vS), membrane (vM) or nucleoprotein gene (vN). Lymphocytes from a TGEV immunized (d/d) swine developed a cytotoxic activity after secondary in vitro stimulation in the presence of vS, vM or vN infected L14 cells. The cytotoxic activity was induced and directed against the homologous vS and vM infected cells but no cytotoxic activity occurred at all against vN infected cells. While vM infected cells induced a cytotoxic activity against vM infected cells only, vS infected cells stimulated a cross-reactive cytotoxic activity against vM and vN infected cells in addition to that against vS infected cells. This latter cytotoxicity may be due to an increase in a non-specific background of Natural Killer or lymphocyte activated killer activity, which is seen also after coculture with wild type vaccinia virus (vW) infected cells. Thus these results are of practical importance in two respects. First, lymphoïd B cell lines represent an excellent tool for determining which viral antigens are recognized by cytotoxic lymphocytes and second, they indicate the need to incorporate the M and S genes into a TGEV vaccine to induce cellular immunity against TGEV.

Animals↗

PubMedDate not supplied

A simple method for evaluating data from an interlaboratory study.

Large-scale laboratory- and method-performance studies involving more than about 30 laboratories may be evaluated by calculating the HORRAT ratio for each test sample (HORRAT = [experimentally found among-laboratories relative standard deviation] divided by [relative standard deviation calculated from the Horwitz formula]). The chemical analytical method is deemed acceptable per se if HORRAT approximately 1.0 (+/- 0.5). If HORRAT is > or approximately 2.0, the most extreme values are removed successively until an "acceptable" ratio is obtained. The laboratories responsible for the extreme values that are removed should examine their technique and procedures. If > or approximately 15% of the values have to be removed, the instructions and the methods should be examined. This suggested computation procedure is simple and does not require statistical outlier tables. Proposed action limits may be adjusted according to experience. Data supporting U.S. Environmental Protection Agency method 245.1 for mercury in waters (manual cold-vapor atomic absorption spectrometry), supplemented by subsequent laboratory-performance data, were reexamined in this manner. Method-performance parameters (means and among-laboratories relative standard deviations) were comparable with results from the original statistical analysis that used a robust biweight procedure for outlier removal. The precision of the current controlled performance is better by a factor of 4 than that of estimates resulting from the original method-performance study, at the expense of rejecting more experimental values as outliers.

Chemistry Techniques, Analytical↗