Quantification of cells with specific phenotypes I: determination of CD4+ cell count per microliter in reconstituted lyophilized human PBMC prelabeled with anti-CD4 FITC antibody.

A surface-labeled lyophilized lymphocyte (sLL) preparation has been developed using human peripheral blood mononuclear cells prelabeled with a fluorescein isothiocyanate conjugated anti-CD4 monoclonal antibody. The sLL preparation is intended to be used as a reference material for CD4+ cell counting including the development of higher order reference measurement procedures and has been evaluated in the pilot study CCQM-P102. This study was conducted across 16 laboratories from eight countries to assess the ability of participants to quantify the CD4+ cell count of this reference material and to document cross-laboratory variability plus associated measurement uncertainties.

Simultaneous determination of membrane CD64 and HLA-DR expression by blood neutrophils and monocytes using the monoclonal antibody fluorescence capability of a routine haematology analyser.

This study reports the design of an immunofluorescent method for the co-determination of neutrophil CD64 (PMN-CD64), monocyte CD64 (MON-CD64) and monocyte HLA-DR (MON-Ia) expression with the Cell-Dyn CD4,000 haematology analyser. Normal PMN-CD64, MON-CD64 and MON-Ia expression, defined as the mean+/-2SD of 25 healthy adults after correction for isotype control staining, corresponded to 17-67, 515-1045 and 170-670 AFU respectively. Analytical reproducibility determined by duplicate analysis of 12 random samples revealed good assay consistency for all three analysed antigens, with day to day variation in normal subjects being relatively minor in significance.