Evaluation of phagocytic function of macrophages in rats after partial splenectomy

Understanding the immunologic properties of the spleen has enabled surgeons to practice splenic conservation surgery. If the upper pole of the spleen can be preserved solely on the upper short gastric vessels, will phagocytic function of macrophages in remnant splenic tissue be affected? The aim of this experimental study was to evaluate the phagocytic function of macrophages in partially resected spleens, with hilar excision preserving the short gastric vessels.

Forty-eight female Wistar albino rats were divided into four groups. Groups 1 and 2 underwent sham operations and groups 3 and 4 underwent partial splenectomy. One milliliter of sodium chloride 0.9% was injected into the abdomen of the rats in groups 1 and 3 and 1 mL of Streptococcus pneumoniae type III as an antigenic stimulus was injected into the abdomen of the rats in groups 2 and 4, 6 weeks after the first operation. Forty-eight hours later, relaparotomy was performed in all animals. India ink was used to determine the capacity of uptake in the splenic phagocytes. To evaluate the phagocytic function of the splenic tissues, histologic examinations were performed according to a macrophage grading system.

All spleens in all four groups were stained black after injection of India ink. Phagocytic activity of macrophages was reduced in the partially splenectomized groups, compared with intact spleen groups (group 3 versus group 1; p < 0.0001, group 4 versus group 2; p < 0.0001). There was a significant difference between groups 1 and 2 according to phagocytic function of macrophages (p = 0.0121). Also, after Streptococcus pneumoniae type III injection as an antigenic stimulus in group 4, we found that the phagocytic functions of macrophages increased compared with those of the sodium chloride 0.9%-injected group 3 after partial splenectomy (p < 0.0001).

Phagocytic function of macrophages in rats decreased after partial splenectomy. Nevertheless, the remnant spleens in rats could be stimulated when challenged with an antigenic stimulus.