The Expression of CR1 and CR3 on Non‐Modulated and Modulated Granulocytes of Healthy Blood Donors as Measured by Flow Cytofluorometry

Complement receptors, CR1 and CR3, on neutrophils increase their cellular spontaneously at 37°Cor after mechanical stress during the cell preparation. We have established a cell preparation procedure and a cytofluorometric immunoassay method to evaluate the receptor expression in vivo in this study. The expression of CRI and CR3 was studied after haemolysis in NH4C1 at different temperatures and incubation intervals. It was shown that cell preparation and receptor analysis must be performed at 15°C or lower to avoid up‐regulation of the receptor structures. Two minutes' Incubation at 20°C was sufficient to modulate the cells in this regard. Granulocytes from healthy blood donors were analysed and the mean fluorescence intensity (MF1), which reflects the number of receptors on (he ceil surface, showed a normal distribution for the CRI (n=158) and CR3 (n=76) expression in the healthy population. The MFI of the two receptors showed a correlation (r=0.71). Granulocytes from all donors could be modulated at 37°C to a similar degree for both receptors (r=0.76), despite the fact that they are supposed to be mobilized from different intracellular pools. A group of patients with localized inflammatory processes, such as sinusitis, differed from the healthy controls. In this group, the CR1 expression was not normally distributed, but IS out of 26 patients (58%) had granulocytes with a CR1 expression exceeding the mean±SD of the normal population.