Surgical Trauma Evokes a Rise in the Frequency of Hematopoietic Progenitor Cells and Cytokine Levels in Blood Circulation

Alterations in the mononuclear cell populations in the blood circulation are among the most characteristic changes after surgical trauma. They reflect changes in the hematopoietic compartment which develop following surgery. The process of mobilization and differentiation of the hematopoietic population is regulated by cytokines known as growth factors for stem and progenitor cells (SCF, IL-1, IL-3, IL-6, IL-1L, TNF, CSFs). Our question was whether operative trauma resulted in the release of the hematopoietic progenitor cells to the blood circulation and an increase in the blood level of cytokines participating in hematopoiesis. The studies were carried out in patients with chronic cholelithiasis, undergoing elective open cholecystectomy under general anesthesia. An increase in the frequency of circulating CD34+ hematopoietic progenitor cells was seen between days 3 and 7 after surgery. Moreover, a significant increase in the percentage of immature cells of myeloid lineage (CD13+, CD14+, CD33+) was seen on the 1st and 3rd postoperative days. This could be the result of an expansion of the total bone marrow cell number after surgery and a subsequent release of these cells into the blood circulation. The changes in blood cell populations were accompanied by an increase in IL-6 on days 1, 3, and 7 following surgery, in IL-6sR on days 10 and 14 and in IL-8 on days 1 and 3. No significant changes in IL-1alpha, IL-1beta, IL-3 and IL-11 were noted. A small rise in GM-CSF was noted in few patients on the 3rd and 7th postoperative days. It is known that IL6 is involved in hematopoiesis, that the IL6-IL-6sR complex may induce both proliferation and differentiation of hematopoietic progenitor cells and that IL8 possesses progenitor cell mobilization properties. The appearance of hematopoietic progenitor cells in the blood following surgery may represent a process for the expansion of the immune cell pool after trauma and maintaining of the reserves at a certain level.