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Natural Killer (NK) Cytotoxicity Profile:
NK cell cytotoxic functional activity is estimated by a standard 4-hour stimulation of effector cells (patient or control peripheral blood mononuclear cells) incubated with target cells (monocytic cell K562 lacking major histocompatibility complex class I expression) labeled with 51Cr. The % cytotoxicity (51Cr release) is measured for a series of effector to target concentrations. Maximal cytotoxicity is measured using a detergent for target cell lysis as an experimental control and spontaneous cytotoxicity in the absence of effector stimulation is also measured.(Unpublished Mayo method)
T- and B-Cell Quantitation by Flow Cytometry:
The T- and B-cell surface marker assay uses monoclonal antibodies to identify the various membrane antigens, and flow cytometry to enumerate the number of cells expressing these differentiation antigens. The results are reported as the percent of lymphocytes that are T-helper (CD3+, CD4+), T-suppressor (CD3+, CD8+), natural killer (CD16+56+, CD3-), and B-lymphocytes (CD19+), and the absolute number of each cell type per mL of blood. The assay is a 4-color, no-wash procedure and the absolute counts are calculated from internal bead standards. In addition, the total lymphocyte count and the helper-suppressor ratio (T[H]/T[S]) is reported.(Hoffman RA, Kung PC, Hansen WP, Goedstien G: Simple and rapid measurement of human T lymphocytes and their subclasses in peripheral blood. Proc Natl Acad Sci USA, 1980:77:4914-4917; US Department of Health and Human Services: Guidelines for performance of CD4+ T-cell determinations in persons with human immunodeficiency virus infection. MMWR Morb Mortal Wkly Rep 1997;46[no. RR-2]:1-29)
N.K. Cytotoxicity: Monday through Friday; Continuously to 2 p.m.
T- and B-Cell QN by Flow Cytometry: Monday through Sunday