The Correlation Between the Percent of Cd3- Cd56+ Cells and Nk Precursor Function

The number and function of human natural killer (nk) cells are generally assessed tomonitor the baseline of immune function, the effect of treatment, the progress ofmalignancy or metastases and diseases. nk cells recognise and kill target cells in the absenceof prior sensitisation and are able to defend the host from infection or prevent theprogression of a disease. human nk cells express cd16 and cd56 which are (massively)being used as a major hallmark for the nk cell. the purpose of this study was to identify theunique subsets of peripheral blood mononuclear cells (pbmc) (%cd3-cd56+ cells) by flowcytometry and to determine whether there is any correlation with functionally matureprogeny of (nkp) precursor after five days of culture.the correlation was analysed using samples obtained from 120 caucasian patients. 20-30rnlof whole blood was collected in sterile tube containing preservative free sodium heparin and asimilar sample was obtained after five days. maturation of nkp required the continuouspresence of recombinant interleukin 2 (ril-2), or interleukin 15 (rll-15) and functionalmaturity ofnk cells was determined by their ability to lyse target cells from the k562 cell line.the nk precursor frequency was measured by limiting dilution analysis (lda), which thenkpf assay was set up with a range of cell dilutions from 40,000 to 625 per 100fll/well in 96well culture plates. at the end of the culture period the k562 cell line labelled with europium(eu-k562) was added and eu release measured in culture supernatants using time-resolvedfluorometry, the pbmc were set up in parallel cultures under various conditions .on day fivecells were collected from culture plates and adjusted to lxl0 cells/ml and then mixed. themixture was incubated and anti cd3 and anti cd56 were added. nk cells were enumerated in120 patients by double staining with a combination of anti-cd3- and anti-cd56+,the results of these lmmunophenotyping studies by flow cytometry showed nocorrelation between the nkpf (natural killer precursor frequency) and the percent of cd3cd56+cells expressed after five days confirming that cd56 was inadequate as a uniquemarker for functional nk cells.