Immune Consequences of Nonoperative Treatment of Splenic Trauma in the Rat Model

To investigate the immunologic consequences of non-operative management of splenic injury, three parameters were studied: survival following pneumococcal sepsis, clearance of blood-borne bacteria, following Hemophilus influenzae challenge, and antibody response to type III pneumococcal capsular polysaccharide. Two hundred twenty-five Sprague-Dawley rats were divided into three groups and subjected either to a splenectomy, a sham operation, or standard blunt trauma. A significant increase in mortality was noted in the splenectomized group as compared with both the traumatized and control groups when challenged with Streptococcus pneumoniae. In both the control and trauma groups, H influenzae cleared significantly within 18 hours. Blood-borne bacteria persisted at the same level for 72 hours in the splenectomized animals. Four and 11 days later, the antibody level in both traumatized and control groups was higher than in the splenectomized subjects (P less than .001). There was no difference in the serum antibody level between the control and trauma groups at four days. However, at 11 days the trauma group showed a significant decrease in the antibody level (P less than .05). It can be concluded that following spontaneously-healing splenic trauma in the rat model, survival, bacterial clearance, and antibody response were all superior to that observed in the splenectomized subjects. In addition, the healed splenic disruption did not impair clearance of blood-borne encapsulated bacteria.