By priming in vitro with allogeneic HLA‐DR compatible and also HLA‐A, B mostly compatible lymphoid cells, PLT cells resulted in recognizing a group of non D/DR allelic antigens provisionally named K, L, M and N. To improve discrimination these bulk primed typing reagents were cloned and expanded. By typing of previously SB typed lymphoblastoid B cell lines (LCL) the provisional specificities could be identified as SB1, 4, 3 and 2, respectively. Typing of 186 unrelated Norwegians gave the following gene frequences: SB1: 0.05, SB2: 0.16, SB3: 0.13, SB4: 0.42 and SB blank: 0.24. No triplets were found, the calculated gene frequencies fit with Hardy‐Weinberg equilibrium, and typing of a B‐DR recombinant family confirmed that the SB locus is situated centromeric to B. Associations between SB and A, B, DR antigens in the same material were generally weak, the most significant associations found were between SB1‐DR3 and SB4‐DR2.
Human alloantisera were investigated for their ability to induce antibody-dependent cellmediated cytotoxicity (AICC) in a micro-plate-system. Ten to 20 x 103 fresh (non-stimd a t e d ) lymphocytes were used as targets, and an effector: target cell ratio of 33:l was usually satisfactory, Harvesting was performed after 8-16 h of incubation. This system proved as reliable as tests in tubes with larger volumes and cell numbers. The HL-A specificity of the sera determined by complement-dependent cytotoxicity (CDC) was found to be completely included in the specificity determined by the AICC test. The latter specificity, however, was broader and the AlCC test also revealed much higher titers of alloantibody activity.When antibodies reacted with HL-A antigens of the effector cells, as revealed by CDC tests, the AICC test was inhibited.By running the test system in niediurn not containing serum with alloantibody activity, the presence of cytotoxic (T) lymphocytes in the effector cell population could also be detected. Thus, the micro-test system is a sensitive test for both pre-existing cellular and humoral immunity against human alloantigens.
Several of the major variable factors in the Syrian hamster embryo/simian adenovirus SA7 (SHE/SA7) viral enhancement assay were identified and the effects of these parameters on assay sensitivity were assessed. The extent of dose-dependent cytotoxicity and enhancement of SA7 transformation of primary SHE target cells by benzo(a)pyrene was examined through analysis of data obtained from 37 assays performed over a 2-year period. The variables analyzed for contribution to assay sensitivity included the number of SA7-induced transformed SHE cell foci enumerated in ten replicate dishes in the negative control condition (background focus count) (range: 26-139); the age of the SHE cell cultures at the time of exposure to benzo(a)pyrene (range: 72-144 hr postseeding); and the source of the pregnant hamsters used to prepare the primary SHE cells (Wilmington colony vs Lakeview colony, Charles River Laboratories, Inc., Wilmington, MA). The benzo(a)pyrene-induced cytotoxicity and enhancement of SA7 transformation responses were found to be independent of each of these variables, within the range of values tested.
A method for measuring the ability of chemicals to enhance focus formation by the highly oncogenic DNA-containing simian adenovirus SA7 is described. The standard test consists of a} pretreatment of target Syrian hamster embryo cells with chemical test articles, b} subsequent treatment of chemically-exposed or control target cells with SA7 virus, and c} determination of cellular toxicity and focus formation in chemically treated and control plates. This paper outlines the procedures for performing the standard test and additionally describes a} methods for preparing the Syrian hamster embryo cells, b} methods for preparing the SA7 virus pools, c) criteria for assay acceptability, and d} criteria used to assign an overall call (positive, negative, or equivocal) to a compound based on the results of multiple individual assays.
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