GRANULOCYTE MARGINATION IN BONE-MARROW - COMPARISON WITH MARGINATION IN THE SPLEEN AND LIVER

The kinetics of radiolabelled granulocytes in the reticuloendothelial system were studied in order to evaluate granulocyte margination in bo ne marrow. A total of 34 patients took part in a two-part study. In th e first part, bone marrow uptake of indium-111-labelled granulocytes w as retrospectively analysed in early (3-h) and late (24-h) images in 2 6 patients, 13 with bronchiectasis and 13 with enclosed abdominal absc esses. The ratios between early and late counts from the bone marrow, spleen, liver and inflammatory lesion were used to quantify granulocyt e margination in bone marrow, postulating that if the lesion to bone m arrow ratio at 24 h exceeds the value at 3 h, then the ''excess'' bone marrow counts on the early images would represent margination. In the second part, this suggestion was prospectively tested using Rutland-P atlak graphical and deconvolution analysis of dynamic data, acquired i n 8 patients undergoing routine scanning with technetium-99m HMPAO-lab elled granulocytes. In the first part of the study, it appeared that t he bone marrow is a regional site of granulocyte margination, like the spleen, with at least one-half of the 3-h marrow signal arising from marginated granulocytes, compared with about two-thirds from the splee n. In the second part, it was found that the gradient of the Patlak pl ot, based on spleen and marrow, continuously decreased, consistent wit h bi-directional movement of cells between these organs and the blood. Granulocyte pooling in the marrow was confirmed with deconvolution an alysis, which generated biphasic retention functions for marrow and sp leen. These curves were also consistent with two-way granulocyte excha nge, and gave mean cell transit times in both organs of about 12 min a nd probabilities of extraction on each pass of 5-10%. We conclude that granulocytes marginate in bone marrow to an extent similar to that in the spleen.