Methods of Splenic Preservation and Their Effect on Clearance of Pneumococcal Bacteremia

Abstract

The intravascular clearance of type 3 Streptococcus pneumoniae was studied in Sprague-Dawley rats. Sham celiotomy was performed on 20 animals while another 20 rats underwent splenectomy. Four weeks later, bacteremia was induced by intraperitoneal (IP) injection of S. pneumoniae. Serial cultures of peripheral blood were obtained. Splenectomy produced significant impairment of intravascular clearance of bacteria compared to that noted among control animals (p less than 0.01). Eighty animals were divided into four equal groups: I--splenectomy, II--50% splenectomy with the upper half left in situ connected to the short gastric vessels, III--50% splenectomy with the lower half left in situ connected to the hilar vessels, and IV--splenectomy with implantation of splenic fragments. Pneumococcus was administered IP 16 weeks later. Rats were killed 6 hours after bacterial challenge. Residual splenic tissue was weighed. There was significantly less splenic tissue in Groups II-IV than noted in sham animals after 16 weeks (p less than 0.01). The type of partial splenectomy did not significantly affect the weight of residual splenic tissue 16 weeks later. Implantation did yield viable splenic tissue, though the amount proved significantly less than that resulting from either type of partial splenectomy (p less than 0.01). Mean bacterial counts with time for short gastric (Group II) and hilar (Group III) remnant animals were significantly different from those for the asplenic (Group I) rats (p less than 0.02 and p less than 0.001, respectively). Animals with splenic implants (Group IV) were not significantly different from asplenic rats (Group I). Animals with hilar splenic remnants proved significantly different from those with short gastric splenic remnants (p less than 0.01). Partial splenectomy offers protection against pneumococcal bacteremia, though preservation of the hilar blood supply affords the most benefit. The utility of splenic implantation remains unproven.

Critical mass of splenic autotransplant needed for the development of phagocytic activity in rats

“…During infections, the sequestration of bacteria induces the synthesis of antibodies in subjects with a preserved spleen. After total splenectomy (TS), the levels of IgG and IgA vary widely and may be normal or elevated, but most of the available data suggest a reduction of IgM [3,7–10]. Furthermore, in patients undergoing TS, the levels of CD4 + T lymphocytes (helper), the proportion of CD4 + /T CD8 + T lymphocytes (helper/suppressor) and the competence of T lymphocytes themselves, in general, is reduced, which may be due to the minimization of the mitogenic responsive capacity of these cells [11].…”

“…Clinical and experimental investigations have shown that, after a certain period, autotransplanted splenic tissue presents morphological regeneration and leads to the recovery of some functions of the spleen [3,6,8,10,12,21–32]. However, it is of fundamental importance to determine the amount of splenic tissue to be autotransplanted – critical mass – for the occurrence of functional regeneration.…”

Partial splenectomy for children with congenital hemolytic anemia and massive splenomegaly

“…To that effect, of the 11 children tested, all were noted to have retained normal or near-normal serum levels of immunoglobulins G and M (IgG and IgM). Previous human and animal studies have shown that partial splenectomy leaving 20% to 30% of normal splenic volume does retain splenic immune function [7,13,14,[20][21][22][23]. Although some animal studies suggested isolated residual splenic tissue from the upper pole or from autotransplantation may not convey equivalent immunologic activity [21,22], other studies have found appropriate splenic morphology, viability, and stimulation of immune function with partial splenectomy supplied by gastric vessels [20,23,24].…”

Postoperative Ergebnisse höhergradiger traumatischer Milzrupturen bei Kindern im Langzeitverlauf

“…In der Literatur wurden jedoch nach Ligatur der A. lienalis in der Kindheit unauffällige Sonografien, Szintigrafien, Immunglobuline, Komplementfaktoren, Antikörpertiter nach Impfungen und sonstige Blutwerte beschrieben [36]. Tierexperimentell konnte gezeigt werden, dass nach partieller Milzresektion ein gewisser Schutz vor einer Pneumokokkeninfektion besteht [37,38]. Die phagozytäre Funktion ist jedoch vermindert und korreliert mit dem Restgewicht [39,40].…”