Hipoesplenismo funcional em transplante renal

Abstract

From ultrasonography (US) observation that reduction of spleen size in kidney transplant recipients (RTRs) occurred after> six months of the procedure, the hypothesis of functional hyposplenism, in part of this group of patients, was raised. Then, we conducted this study, to verify the occurrence of the phenomenon, to determine its prevalence, to compare diagnostic methods used for its diagnosis and to verify its association with immunosuppressive drugs used to maintain renal graft function. The anatomical evaluation of the spleen included the determination of its longitudinal diameter (DLB) and Doppler data, obtained in splenic and intrasplenic arteries. The spleen evaluation of the phagocytic and immunological functions included the presence of Howell-Jolly (HJ) corpuscles in the peripheral blood smear, the 99mTc-Sn-colloidal hepatosplenic scintigraphy and quantification (percentage and absolute number) of B-cell subpopulations, in peripheral blood, by flow cytometry. We observed changes in all evaluations and we compared their results to each other. In the cases that the results of HJ and scintigraphy were divergent (HJ positive and normal scintigraphy), we observed that the occurrence of hematological alteration was more frequent in patients with lower DLB, suggesting that the mass of functioning splenic tissue ("critical mass") would be lower than the necessary for the removal of senescent red blood cells from the circulation. When we compared the groups using calcineurin inhibitors (IC) or sirolimus (SRL), association between lower DLB and SRL use was found, without splenic dysfunction being attributable to this drug. When groups using MMF based combinations were compared, according to the distributions of the different B-cell subtypes, a statistically significant association between mycophenolate-steroid therapy (MMF-ST) and reduction in the proportion of B switched memory cells were found (p = 0.028). According to the abnormality of the phagocytic function, determined by HJ presence, the prevalence of hyposplenism in RTRs was estimated at 30%. If the presence of HJ was associated with the reduction of radiocolloid uptake in scintigraphy, at 29.09%. If taken together, the phagocytic and immunological functions of the spleen, the prevalence of the condition was calculated estimated at 14.55%. In conclusion, all the results allowed to confirm the occurrence of functional hyposplenism in RTRs, in high prevalence, to define that the US-Doppler of the spleen is a method that can point to the existence of the phenomenon and to verify how the disorder correlates with the dose and the time of exposure to MMF (p <0.001).