Uptake of latex particles by macrophages: characterization using flow cytometry.

Flow cytometry can be used to characterize the uptake of particles by small samples of pulmonary macrophages both quickly and accurately. We found that there was a linear relationship between the number of fluorescent latex particles and the fluorescent intensity associated with each cell up to 47 particles/cell. Macrophages lavaged from the lungs of Syrian golden hamsters were metabolically and functionally stable for 3 h of incubation; the average intracellular concentrations of Na+ and K+ were 29 +/- 2 and 158 +/- 6 mM, respectively. Particle uptake was significantly inhibited by removing divalent cations with ethylenediaminetetraacetic acid and lowering the incubation temperature (37 degrees C) to 24 and 3 degrees C. The cell-to-cell variability in the uptake of particles was greater than the Poisson distribution would predict based on the mean number of particles per cell.