The peripheral kinetics of human radiolabelled eosinophils.

Peripheral kinetics of eosinophils were studied in three subjects with normal hematological conditions after a puls labelling with 0.1 mu Ci 3HTdR per g bodyweight. The computer recorded labelling index curves (LI) presented an undulating course in all three subjects. Eosinophils proved to disappear randomly. The emergence time of 13 h was followed by the first LI peak of 17%. 80 h p.i. a massive immigration of highly labelled cells with a LI value of 58% was encountered. 50% of eosinophils remained labelled up to 11th day p.i. Cells with different labelling intensities arrayed to grain groups presented a clear synchronism of their LI-curves which become less clear with time. The mean t/2-value for all labelling intensities amounted to 8 h. Cells with low labelling intensities had a longer and the highly labelled eosinophils a much shorter t/2-values. These effects suggest the existence of two proliferating eosinophil precursor pools: a rapid and a slow one. The early influx of low labelled as well as the late emergence of great number of highly labelled eosinophils are in good accord with this assumption. The time span for S-phase indirectly calculated revealed 13 h. The myelocyte generation time was estimated with 34 h. Both values were found to well agree with the corresponding data for other granulocytes as reported on, in the literature.