Monitoring dendritic cells in clinical practice using a new whole blood single-platform TruCOUNT assay

Dendritic cells (DC) from distinct DC subsets are essential contributors to normal human immune responses. Despite this, reliable assays that enable DC to be counted precisely have been slow to evolve. We have now developed a new single-platform flow cytometric assay based on TruCOUN(TM) beads and the whole blood Lyse/No-Wash protocol that allows precise counting of the CD14(-) blood DC subsets: CD11c(+)CD16(-) DC, CD11c(+)CD16(+) DC, CD123(hi) DC, CD1c(+) DC and BDCA-3(+) DC. This assay requires 50 mul of whole blood; does not rely on a hematology blood analyser for the absolute DC counts; allows DC counting in EDTA samples 24 It after collection; and is suitable for cord blood and peripheral blood. The data is highly reproducible with intra-assay and inter-assay coefficients of variation less than 3% and 11%, respectively. This assay does not produce the DC-T lymphocyte conjugates that result in DC counting abnormalities in conventional gradient-density separation procedures. Using the TruCOUNT assay, we established that absolute blood DC counts reduce with age in healthy individuals. In preliminary studies, we found a significantly lower absolute blood CD11c(+)CD16(+) DC count in stage III/IV versus stage I/II breast carcinoma patients and a lower absolute blood CD123(hi) DC count in multiple myeloma patients, compared to age-matched controls. These data indicate that scientific progress in DC counting technology will lead to the global standardization of DC counting and allow clinically meaningful data to be obtained. (C) 2003 Elsevier B.V. All rights reserved.

Development of a cell culture method for quantal assay of strain I-2 of Newcastle disease virus

Repeated titrations of strains of Newcastle disease virus (NDV) are more conveniently undertaken in cell cultures rather than in embryonated eggs. This is relatively easy with mesogenic and velogenic strains that are cytopathic to various cell lines, but is difficult with avirulent Australian isolates that are poorly cytopathic. Strain V4 for example has been shown to be pathogenic iin vitro only to of chicken embryo liver cells. Strain 1-2 was reported to produce cytopathic effect (CPE) on chicken embryo kidney (CEK) cells. The present studies confirmed this observation and developed a quantal assay. CEK cells infected with strain 1-2 developed CPE characterized by degeneration, rounding, granularity and vacuolation, and the formation of synctia. End points were readily established by microscopic examination of fixed and stained cells. In virus infectivity studies on strain 1-2, where multiple titrations are required and where large numbers of samples are used, titration using CEK cell grown in microtitre plates is recommended. Such studies may not be feasible in embryonated eggs.