Blood concentrations of G-CSF and myelopoiesis in patients undergoing aortocoronary bypass surgery

Abstract

The pattern of changes in leukocyte counts and the blood concentration of G-CSF were observed in 15 patients undergoing aortocoronary bypass surgery. Myelopoietic function was assessed by examining the myelogram and performing flow cytometry to identify human leukocyte differentiation antigens on bone marrow aspirates obtained from the sternum when opening and closing the sternotomy. The blood concentration of G-CSF increased gradually after removal of the aortic cross clamp and peaked on the first postoperative day (232 +/- 98 ngml). The white blood cell count also increased during the operation and peaked on the second postoperative day, demonstrating a threefold increase (15,800 +/- 2700). Granulocytes represented most of the increase, while lymphocytes and monocytes showed no significant changes. The myelogram showed that the percentages of myeloblasts, promyelocytes, and metamyelocytes did not change; however, the percentage of myelocytes increased significantly during surgery (14.0 +/- 2.5% vs. 17.3 +/- 3.5%, p < 0.05). The number of mature myelocytes (LFA-1 beta and Leu-15 positive) decreased significantly (p < 0.01 and p < 0.05) during surgery. With the two-color method, the ratio of immature myelocytes (MCS-2 negative and Leu-15 negative) increased significantly (p < 0.01). The ratio of myeloblasts (Leu-11 and HLA-DR positive) and the ratio of stem cells (CD 34 and MY-9 positive) did not increase significantly during the operation. G-CSF concentrations increase substantially during aortocoronary bypass surgery and may be responsible for the rise in granulocyte and total leukocyte counts, as well as for the increase in immature myelocytes seen on bone marrow examination.

Circulating CD10−/CD16low neutrophils provide a quantitative index of active bone marrow neutrophil release

“…The neutrophil phenotype commonly seen during active bone marrow neutrophil release is unique and suggestive of neutrophil membrane immaturity. CABG, a controlled inflammatory stimulus associated with bone marrow neutrophil release (Quiroga et al, 1985;Usui et al, 1997), provides a useful in vivo model to investigate changes in the circulating neutrophil pool during acute inflammation. We have identified that over 40% of the circulating neutrophil pool following CABG exhibits a CD10 ) /CD16 low phenotype, that this subpopulation is functionally significant and may provide a useful quantitative measure of the bone marrow contribution to neutrophilia.…”