In vitro study of the long-term effects of post-traumatic splenectomy on cellular immunity

The purpose of this study was to investigate the effect of splenectomy on cellular immunity. We studied the cellular phenotype and type 1 interferon‐γ, interleukin‐2 (IL‐2)] and type 2 (IL‐4 and IL‐10) cytokine‐producing peripheral blood CD4⁺ and CD8⁺ T lymphocytes in 22 healthy adults who had undergone post‐traumatic splenectomy about 1 to 35 years ago. Splenectomy resulted in a long‐term reduction of the percentage of CD4⁺CD45RA⁺ cells and a late increase of the percentage and absolute numbers of T‐cell receptor γ/δ cells. Stimulation with Staphylococcal enterotoxin B resulted in normal IL‐2 production by CD4⁺ T cells, indicating that the naïve cells were not anergic. Splenectomy also resulted in long‐term priming of both CD4⁺ and CD8⁺ T cells. During the first 8 years, both type 1 and type 2 CD4⁺ T cells were primed to varying degrees. About 8 years later, the percentage of primed type 2 CD4⁺ T cells subsided, but that of type 1 CD4⁺ T cells, although decreased, remained detectable over a longer period. Priming of CD8⁺ T cells persisted throughout the study period. The long‐term priming of type 1 CD4⁺ and CD8⁺ T cells, which may result in partial impairment of T‐cell functions, may explain reported defects of immune responses to recall antigens in splenectomized individuals. In addition, changes in the profile of primed CD4⁺ T cells with time may be clinically relevant to relapses in autoimmune thrombocytopenia after splenectomy.