Hemorrhagic shock has been shown to alter bone marrow (BM) myelopoiesis. Isolated hemorrhagic shock is uncommon after trauma and the combined effect of tissue injury and shock on myelopoiesis is unknown. We studied the growth of BM granulocyte-macrophage colony forming units (CFU-GM) following shock and soft tissue injury. Rats were anesthetized and allocated into one of four groups: CONTROL, sham neck dissection; SHOCK, rats were bled to a mean BP of 45 mmHG for 45 min and resuscitated with shed blood and saline; TURP, soft tissue injury was induced by turpentine 0.5 ml/100 g SQ into the hindquarter; SHOCK + TURP, rats received TURP just before SHOCK as described above. Groups (n = 6) were sacrificed 1, 3, and 5 days after treatment. BM cells plated for CFU-GM and splenic macrophages were cultured for IL-1 production. Unstimulated splenic macrophage production of IL-1α was not different for any group except Day 5 turpentine animals. TURP induced a significant increase in CFU-GM on Day 1 compared to that in control (47 ± 22 vs 21 ± 11; P < 0.05). SHOCK completely abolished this response to TURP. Both the SHOCK and TURP alone increased CFU-GM on Day 5 compared to that in CONTROL but there was no additive effect in the SHOCK + TURP group. These data show that the BM response to combined soft tissue injury and shock (TURP + SHOCK) appears similar to that of SHOCK alone and that hemorrhagic shock appears to be a significant immunosuppressive factor in the regulation of myelopoiesis following injury.
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