Hyposplenism in Long-Standing Renal Transplant Recipients

Abstract

Background: In our unit, the routine screening for kidney recipients include surveillance with sonography/Doppler after surgery, irrespective of graft function, and at least once a year later on. Almost all studies are performed by an experienced trained nephrologist, who noticed that patients soon after post-transplant showed a larger spleen than patients with long-standing functioning renal graft. These findings, together with the report that in chronic graft versus host disease in bone marrow transplant recipients develop spleen size reduction associated with hyposplenism, and hyposplenism is known to increase susceptibility to infections with encapsulated bacteria, prompted the authors to decide to study splenic function in renal transplant recipients based on sonographic/Doppler and haematological parameters. Methods: The study design was a cross-sectional survey based on single samples. We enrolled two groups: one in the immediate postoperative days (early group) and the other with functioning long-standing kidney graft (late group). To evaluate splenic function, two studies were carried out. First, longitudinal diameter of the spleen and resistivity index of splenic artery at hilum and intrasplenic were measured. All sonograms were performed by a single observer. Second, stained with Giemsa peripheral blood smears (PBS) were reviewed for the presence of Howell-Jolly bodies, using a light microscope viewing. All blood samples were examined by a single observer. Examination of the PBS for Howell-Jolly bodies was restricted to the late group. According to the result, late group was further divided in Howell-Jolly bodies positive (HJ+) or negative (HJ−). Spleen size determination by ultrasonography and Doppler studies were performed in both groups. Immunosuppressive drug regimen used corticosteroid, azathioprine or mycophenolate mofetil and calcineurin inhibitor or mTOR inhibitor. Results: We studied 52 unselected adult patients who had undergone kidney transplantation from a deceased donor and 24 from living donor. The mean age was 48.4±11.5 years (range: 23-74 years). Mean follow up was 11.4±14.2 days for early group (range: 1-68 days) and 2698±1177 days for late group (range: 215-6446 days). Late group had smaller spleen than early group (95.8±16.5 vs 106.3±16.3 mm, p=0.010). Howell-Jolly bodies were found in 52% (24/46) of patients. Intrasplenic resistivity index tended to be higher in HJ+ patients (0.57±0.09 vs 0.51±0.09, p=0.055). There was no correlation between Howell-Jolly detection and immunosuppressive drug regimen. Serum creatinine level was the same despite Howell-Jolly detection or not. Discussion: The presence of Howell-Jolly bodies in the peripheral blood red cells is considered an indicator of hyposplenism. Our findings that a group of transplant patients may develop significant spleen size reduction and detection of Howell-Jolly bodies associated with increased intrasplenic resistivity index suggest splenic dysfunction in these patients, yet the clinical significance of these findings to the outcome of the graft is unknown. Nevertheless, poor splenic function may play a role in the vulnerability to infections in transplant recipients.