Observations on NK cells, K cells and on their function a long time after posttraumatic splenectomy

Effect of non-operative management (NOM) of splenic rupture versus splenectomy on the distribution of peripheral blood lymphocyte populations and cytokine production by T cells

Post-traumatic splenectomy is associated with increased postoperative morbidity and mortality and long-term impairment of humoral and cellular immunity. Alternatives to surgery have been developed to minimize or avoid the immediate and/or long-term complications of splenectomy. Herein we investigated the long-term effect of non-operative management (NOM) of the traumatic rupture of the spleen on the distribution of peripheral blood (PB) lymphocyte populations and cytokine production by T cells. PB samples were drawn from six NOM patients, 13 age-matched adults who had undergone splenectomy after trauma (SP patients) and 31 age-matched controls. Cellular phenotypes and the intracellular production of interferon (IFN)-gamma, interleukin (IL)-2, IL-4 and IL-10 cytokines in T cells were determined in whole blood +/- mitogens by flow cytometry. NOM patients did not show any changes in the absolute numbers of lymphocytes or the distribution of their subsets, compared to the controls. In contrast, SP patients showed a sustained increase in the percentage and/or absolute numbers of lymphocytes, CD8 T cells, activated CD8 T cells, natural killer (NK) T cells, NK cells and gammadelta T cells, and a reduction in naive CD4 T cells. The constitutive or induced cytokine production by T cells of the NOM group was similar to the control group, whereas SP patients had increased percentages of constitutive IL-2- and IFN-gamma-producing CD8 T cells and IFN-gamma-producing CD4 T cells. Our findings indicate collectively that the healing process in NOM does not affect the architecture of the spleen to such an extent that it would lead to long-term alterations of the proportions of PB lymphocytes or the T cell cytokine profiles.

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-gamma, 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 gamma/delta 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.

On the mechanism of post-splenectomy leukocytosis in mice

BACKGROUND

Increased number of peripheral white blood cells (PWBCs) has been noted after removal of the spleen.

DESIGN

To clarify the possible mechanisms by which splenectomy affects the PWBC number, the percentage of apoptotic PWBCs, the number and migration rate of peritoneal cells, as well as the 3H-TdR incorporation into PWBCs, were examined in splenectomized, sham-operated and control mice. In addition, the effect of control plasma injected to splenectomized animals on the number of PWBCs was examined.

RESULTS

One and two months after splenectomy the PWBC counts significantly increased, whereas the percentage of apoptotic PWBCs and the number of cells in the peritoneal cavity decreased in comparison with that of the control and sham-operated mice. Seventeen days after injection of carboxy-fluorescein diacetate succinimidyl ester (CFSE)-labelled peritoneal cells into the peritoneal cavity of the animals, their number was significantly higher in the peripheral blood and lower in the peritoneal cavity of the splenectomized animals in comparison with that of the control and sham-operated mice. Injection of control plasma into the splenectomized mice prevented the development of postsplenectomy leukocytosis. Finally, 3H-TdR incorporation into nonstimulated and Con A stimulated PBMCs from the splenectomized mice was higher as compared with cells from the control and sham-operated mice.

CONCLUSIONS

The results of the study present several mechanisms that may clarify the cause of postsplenectomy leukocytosis.

Overwhelming postsplenectomy infection

The incidence of overwhelming sepsis in asplenic patients is low. It carries, however, an unacceptably high morbidity rate and mortality rate. The risk of development is related to the age of the patient as well as the duration since and the reason for splenectomy. It may also occur in functionally hyposplenic states. The rapidly lethal clinical course demands intense efforts toward prevention by both physician and patient, rapid recognition within the initial medical setting, and aggressive intervention with broad-spectrum antibiotics and other supportive measures.

Natural immunity and chronic exercise in rats. The involvement of the spleen and the splenic nerves

We have previously shown that voluntary running for 4-5 weeks in the spontaneously hypertensive rat (SHR) significantly increased in natural cytotoxic mechanism in vivo, measured as clearance of 51Cr YAC-1 lymphoma cells from the lungs. In the present study, we have studied the possible role of the spleen and the splenic nerves in this augmentation. The SHR were randomly allocated to either a voluntary exercise group or a sedentary control group. After four weeks of exercise the runners and sedentary control SHR were further assigned to one of four groups: 1) no surgery, 2) sham operation, 3) splenic nerve section and 4) splenectomy. Splenectomy drastically reduced in vivo cytotoxicity in both runners and sedentary controls, but in vivo cytotoxicity of splenectomized voluntary runners was significantly higher than that of splenectomized sedentary control animals. Selective denervation of the spleen did not affect the in vivo cytotoxicity. These results indicate that the enhanced in vivo natural cytotoxic mechanism following voluntary chronic exercise in SHR is partly dependent on intact splenic function. However, this enhancement does not seem to be mediated by the splenic sympathetic nerves.

Cancer risk after splenectomy

BACKGROUND

Splenectomy may have an impact on immunologic function. To the authors' knowledge, the only previous epidemiologic study investigating cancer risk among patients splenectomized because of trauma reported no increased cancer risk. In contrast, several investigations have suggested that splenectomy in patients with Hodgkin's disease increases the risk for secondary leukemia independent of treatment.

METHODS

To evaluate the cancer risk of patients who underwent splenectomy after traumatic rupture of the spleen, 1103 patients were identified between 1977 and 1989 through Danish hospital discharge records. Another 5212 splenectomized patients also were identified to perform additional analyses for assessing cancer risk subsequent to splenectomy for nontraumatic indications including benign and malignant conditions. Cancer occurrence was determined by performing a linkage to the Danish Cancer Registry. For comparison, expected numbers of cases of cancer were calculated from national cancer incidence rates.

RESULTS

The number of cancer cases observed among posttraumatic splenectomized patients matched the expected number (relative risk = 1.0; n = 20; 95% confidence interval = 0.6-1.6) in an average follow-up of 6.8 years. Additional analyses identified possible excesses of a number of site-specific neoplasms among certain subgroups of patients undergoing splenectomy for nontraumatic reasons, but the numbers in the subgroup analyses were small.

CONCLUSIONS

No increased risk for cancer was observed among patients who underwent splenectomy because of trauma. However, an increased risk for some specific cancer sites was found in patients who underwent splenectomy for nontraumatic reasons, although the effect of treatments for underlying disease and lifestyle habits such as cigarette smoking could not be ruled out in explaining these excess risks.

Development of chronic lymphocytic leukaemia after posttraumatic splenectomy

In the course of a post-splenectomy follow-up study, 2 out of 102 patients who had been splenectomized after an abdominal trauma were found to have developed chronic lymphocytic leukaemia 5 and 31 years after splenectomy, respectively. The possible association between splenectomy and secondary leukaemia is discussed.