An investigation of vascular anomalies centers' transition of care practices.

This study aims to examine transition of care (TOC) practices of multidisciplinary vascular anomalies centers (VACs). Thirty-seven of 71 VAC leaders to whom the survey was sent completed the questionnaire. TOC and transfer practices varied with only 16% of VACs having TOC programs. The most frequently cited barriers to developing a TOC program were lack of resources and difficulty finding expert adult providers.

Food insecurity, housing instability, and dietary quality among children with sickle cell disease: Assessment from a single urban center.

BACKGROUND: Food insecurity and housing instability, both social determinants of health (SDoH), disproportionately affect economically unstable, under-resourced US communities in which children with sickle cell disease (SCD) live. Association between these SDoH markers and dietary quality among children with SCD is unknown. PROCEDURES: We assessed a cross-sectional sample of dyadic parent-child patients and young adult patients up to age 21 from one pediatric SCD center. Food insecurity, housing instability, and dietary quality were measured using validated US instruments and a food frequency questionnaire. Better dietary quality was defined using US dietary guidelines. Multivariate regression assessed for associations among dietary quality and food insecurity with or without (±) housing instability and housing instability alone. RESULTS: Of 100 enrolled participants, 53% were Black and 43% Hispanic; mean age 10.6 ± 5.6 years. Overall, 70% reported less than or equal to one economic instability: 40% housing instability alone and 30% both food insecurity and housing instability. Eighty percent received more than or equal to one federal food assistance benefit. Compared to no economic instability, food insecurity ± housing instability was significantly associated with higher intake of higher dairy and pizza, while housing instability alone was significantly associated with higher dairy intake. Food insecurity ± housing instability was significantly associated with lower intake of whole grains compared to housing instability alone. CONCLUSIONS: Our sample reported high frequencies of both food insecurity and housing instability; having more than or equal to one SDoH was associated with elements of poorer diet quality. Screening families of children with SCD for food insecurity and housing instability may identify those with potential nutrition-related social needs.

Sickle cell disease in the new era: advances in drug treatment.

Sickle cell disease is an inherited blood disorder afflicting an estimated 100,000 individuals in the United States and over 20 million people worldwide. The disease is heralded as the first molecular disease. However, despite its genetic simplicity, the pathophysiologic processes leading to its clinical sequelae are complex, heterogeneous and interrelated, making drug development to treat the disease challenging. For over two decades only one drug, hydroxyurea, had been used as disease-modifying therapy. New pharmacologic agents are rapidly evolving with three new drugs, with different mechanisms of action, approved by the United States Food and Drug Administration in recent years (L-glutamine, crizanlizumab and voxelotor). Several therapeutic approaches targeting different pathways in the disease pathophysiology are being investigated. These include inhibition of hemoglobin S polymerization such as by fetal hemoglobin induction or by increasing hemoglobin oxygen affinity, as well as intervention of downstream pathways including inhibiting cellular adhesion, reducing inflammation and oxidant stress, modulating platelet activation and coagulation abnormalities, and targeting nitric oxide signaling. This review will provide an overview of these therapeutic strategies, discuss the four currently approved drugs in detail, and summarize ongoing clinical trials of new drugs or drug indications for the treatment of sickle cell disease in different phases of development excluding those related to cellular therapies.

Validation of a Questionnaire to Identify Respiratory Tract Infections in Children With Sickle Cell Disease.

BACKGROUND: No validated questionnaires have been published that are specific for identifying respiratory infections in children with sickle cell disease (SCD). METHODS: A questionnaire was developed that included 6 respiratory symptoms (difficulty breathing, wheezing, fever, cough, runny or stuffy nose, and sore throat) to identify respiratory events for a clinical trial. The questionnaire results were compared with identification of viral respiratory pathogens from nasal samples by reverse transcriptase polymerase chain reaction. RESULTS: Eighty questionnaire responses (40 with symptom/s and 40 without) paired with isolation of viral respiratory pathogen from nasal samples were obtained from 53 children with SCD, ages 4 to 18 years over 2 separate periods in different seasons. The questionnaire yielded a sensitivity of 82%, specificity of 72% with an overall accuracy of 76%. The kappa value was 0.53, indicating moderate agreement, and the Fleiss' kappa test statistic was 4.77 with P<0.001, indicating that agreement between the 2 methods was not by chance. CONCLUSION: These results provide evidence for validity of this 6-symptom respiratory questionnaire in identification of respiratory viral infections for use in SCD-related research.

Response to Long-term Vitamin D Therapy for Bone Disease in Children With Sickle Cell Disease.

Patients with sickle cell disease (SCD) are at risk for bone fragility from multiple factors including vitamin D deficiency. To date, no studies have evaluated the efficacy and safety of long-term vitamin D therapy for bone disease in children with SCD. We report a cohort of 4 children with SCD found to have severe vitamin D deficiency, secondary hyperparathyroidism, and abnormal bone mineral density treated with monthly high-dose oral cholecalciferol over 2 years. All patients exhibited a positive response to therapy without hypervitaminosis D or hypercalcemia. Further studies are needed to standardize guidelines for optimal vitamin D dosing and prevention of toxicity.

Enhanced Long-Term Brain Magnetic Resonance Imaging Evaluation of Children with Sickle Cell Disease after Hematopoietic Cell Transplantation.

Progressive neurovasculopathy in children with sickle cell disease (SCD) results in decreased cognitive function and quality of life (QoL). Hematopoietic cell transplantation (HCT) is believed to halt progression of neurovasculopathy. Quantitative analysis of T2-weighted fluid attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) for white matter hyperintensity (WMH) burden provides a meaningful estimate of small vessel cerebrovascular disease. We asked if quantitative analysis of WMH could complement standardized clinical assessment of MRI/magnetic resonance angiography (MRA) for assessing SCD central nervous system vasculopathy before and after HCT. Retrospective longitudinal clinical examination of scheduled annual MRI/MRA and quantitative analysis of WMH were performed before and 1 to 7 years after HCT at scheduled annual intervals, along with QoL measurements, in children who had engrafted after HCT. Of 18 patients alive and persistently engrafted (median age, 9.1 years), pretransplantation MRI demonstrated that 9 and 5 had sickle-related stroke and/or small infarcts, respectively. Patients were divided into WMH severity tertiles based on pretransplantation WMH volumes. MRI and WMH were assessed 1 to 7 years after HCT. MRI/MRA and WMH volume were stable or slightly better in 17 of 18 patients. By parent- and self-report, post-HCT QoL improved for children in the lowest WMH tertile significantly more than in the other groups. Based on this single-institution retrospective sample, we report that WMH appears to quantitatively support MRI-based findings that HCT stabilizes long-term small and large vessel cerebrovascular changes and is associated with the degree of improved QoL. While confirmation in larger prospective studies and evaluation by neurocognitive testing are needed, these findings suggest that WMH is a useful biomarker of neurovasculopathy after transplantation for SCD.

Hydroxycarbamide versus chronic transfusion for maintenance of transcranial doppler flow velocities in children with sickle cell anaemia-TCD With Transfusions Changing to Hydroxyurea (TWiTCH): a multicentre, open-label, phase 3, non-inferiority trial.

BACKGROUND: For children with sickle cell anaemia and high transcranial doppler (TCD) flow velocities, regular blood transfusions can effectively prevent primary stroke, but must be continued indefinitely. The efficacy of hydroxycarbamide (hydroxyurea) in this setting is unknown; we performed the TWiTCH trial to compare hydroxyurea with standard transfusions. METHODS: TWiTCH was a multicentre, phase 3, randomised, open-label, non-inferiority trial done at 26 paediatric hospitals and health centres in the USA and Canada. We enrolled children with sickle cell anaemia who were aged 4-16 years and had abnormal TCD flow velocities (≥ 200 cm/s) but no severe vasculopathy. After screening, eligible participants were randomly assigned 1:1 to continue standard transfusions (standard group) or hydroxycarbamide (alternative group). Randomisation was done at a central site, stratified by site with a block size of four, and an adaptive randomisation scheme was used to balance the covariates of baseline age and TCD velocity. The study was open-label, but TCD examinations were read centrally by observers masked to treatment assignment and previous TCD results. Participants assigned to standard treatment continued to receive monthly transfusions to maintain 30% sickle haemoglobin or lower, while those assigned to the alternative treatment started oral hydroxycarbamide at 20 mg/kg per day, which was escalated to each participant's maximum tolerated dose. The treatment period lasted 24 months from randomisation. The primary study endpoint was the 24 month TCD velocity calculated from a general linear mixed model, with the non-inferiority margin set at 15 cm/s. The primary analysis was done in the intention-to-treat population and safety was assessed in all patients who received at least one dose of assigned treatment. This study is registered with ClinicalTrials.gov, number NCT01425307. FINDINGS: Between Sept 20, 2011, and April 17, 2013, 159 patients consented and enrolled in TWiTCH. 121 participants passed screening and were then randomly assigned to treatment (61 to transfusions and 60 to hydroxycarbamide). At the first scheduled interim analysis, non-inferiority was shown and the sponsor terminated the study. Final model-based TCD velocities were 143 cm/s (95% CI 140-146) in children who received standard transfusions and 138 cm/s (135-142) in those who received hydroxycarbamide, with a difference of 4·54 (0·10-8·98). Non-inferiority (p=8·82 × 10(-16)) and post-hoc superiority (p=0·023) were met. Of 29 new neurological events adjudicated centrally by masked reviewers, no strokes were identified, but three transient ischaemic attacks occurred in each group. Magnetic resonance brain imaging and angiography (MRI and MRA) at exit showed no new cerebral infarcts in either treatment group, but worsened vasculopathy in one participant who received standard transfusions. 23 severe adverse events in nine (15%) patients were reported for hydroxycarbamide and ten serious adverse events in six (10%) patients were reported for standard transfusions. The most common serious adverse event in both groups was vaso-occlusive pain (11 events in five [8%] patients with hydroxycarbamide and three events in one [2%] patient for transfusions). INTERPRETATION: For high-risk children with sickle cell anaemia and abnormal TCD velocities who have received at least 1 year of transfusions, and have no MRA-defined severe vasculopathy, hydroxycarbamide treatment can substitute for chronic transfusions to maintain TCD velocities and help to prevent primary stroke. FUNDING: National Heart, Lung, and Blood Institute, National Institutes of Health.

Longitudinal Analysis of Echocardiographic Abnormalities in Children With Sickle Cell Disease.

BACKGROUND: Cardiac abnormalities have been described in echocardiograms of children with sickle cell disease (SCD). However, longitudinal studies investigating progression of echocardiographic abnormalities across the pediatric age spectrum in SCD are lacking. METHODS: A retrospective longitudinal analysis of 829 echocardiograms from pediatric patients with SCD at steady-state was performed. Left heart parameters included left ventricular end-systolic, end-diastolic diameters, fractional shortening, and mass. Right ventricular pressure was estimated by tricuspid regurgitation gradient. Tricuspid regurgitation gradient ≥25 mm Hg, a z-score ≥2 for LV parameters and ≤-2 for left ventricular fractional shortening were considered abnormal. RESULTS: Kaplan-Meier analysis revealed that echocardiographic abnormalities were detected by 5 years of age, and the cumulative incidence progressively increased throughout childhood. Age, male gender, HbSS and Sß thalassemia genotype, white blood cell count, platelet count, total bilirubin, admissions for pain crises and acute chest syndrome were positively, whereas hemoglobin was negatively associated with cardiac abnormalities. CONCLUSION: Cardiac abnormalities began early in childhood and progressively increased with age. Our study highlights the high cumulative incidence of cardiac abnormalities in children with SCD, which could represent a marker of disease severity.

Effects of hydroxyurea treatment for patients with hemoglobin SC disease.

Although hemoglobin SC (HbSC) disease is usually considered less severe than sickle cell anemia (SCA), which includes HbSS and HbS/ß(0) -thalassemia genotypes, many patients with HbSC experience severe disease complications, including vaso-occlusive pain, acute chest syndrome, avascular necrosis, retinopathy, and poor quality of life. Fully 20 years after the clinical and laboratory efficacy of hydroxyurea was proven in adult SCA patients, the safety and utility of hydroxyurea treatment for HbSC patients remain unclear. Recent NHLBI evidence-based guidelines highlight this as a critical knowledge gap, noting HbSC accounts for ∼30% of sickle cell patients within the United States. To date, only 5 publications have reported short-term, incomplete, or conflicting laboratory and clinical outcomes of hydroxyurea treatment in a total of 71 adults and children with HbSC. We now report on a cohort of 133 adult and pediatric HbSC patients who received hydroxyurea, typically for recurrent vaso-occlusive pain. Hydroxyurea treatment was associated with a stable hemoglobin concentration; increased fetal hemoglobin (HbF) and mean corpuscular volume (MCV); and reduced white blood cell count (WBC), absolute neutrophil count (ANC), and absolute reticulocyte count (ARC). Reversible cytopenias occurred in 22% of patients, primarily neutropenia and thrombocytopenia. Painful events were reduced with hydroxyurea, more in patients >15 years old. These multicenter data support the safety and potentially salutary effects of hydroxyurea treatment for HbSC disease; however, a multicenter, placebo-controlled, Phase 3 clinical trial is needed to determine if hydroxyurea therapy has efficacy for patients with HbSC disease.

Liver iron concentration measurements by MRI in chronically transfused children with sickle cell anemia: baseline results from the TWiTCH trial.

Noninvasive, quantitative, and accurate assessment of liver iron concentration (LIC) by MRI is useful for patients receiving transfusions, but R2 and R2* MRI techniques have not been systematically compared in sickle cell anemia (SCA). We report baseline LIC results from the TWiTCH trial, which compares hydroxyurea with blood transfusion treatment for primary stroke prophylaxis assessed by transcranial Doppler sonography in pediatric SCA patients. Liver R2 was collected and processed using a FDA-approved commercial process (FerriScan®), while liver R2* quality control and processing were performed by a Core Laboratory blinded to clinical site and patient data. Baseline LIC studies using both MRI techniques were available for 120 participants. LICR2* and LICR2 results were highly correlated (r(2) = 0.93). A proportional bias of LIC(R2*)/LIC(R2), decreasing with average LIC, was observed. Systematic differences between LICR2* and LICR2 were also observed by MRI manufacturer. Importantly, LICR2* and LICR2 estimates had broad 95% limits of agreement with respect to each other. We recommend LICR2 and LICR2* not be used interchangeably in SCA patients to follow individual patient trends in iron burden.

Vitamin D deficiency and acute vaso-occlusive complications in children with sickle cell disease.

BACKGROUND: Vitamin D is increasingly recognized for its roles in non-skeletal disorders. Patients with sickle cell disease (SCD) have a high prevalence of vitamin D deficiency but data are limited with respect to possible associations between low vitamin D and acute vaso-occlusive complications. We examined whether vitamin D deficiency is associated with acute pain and acute chest syndrome (ACS) in children with SCD. PROCEDURE: A cross-sectional study was conducted in 95 children with SCD who had serum 25-hydroxyvitamin D (25-OHD) measured during comprehensive care examinations. History of acute pain and ACS within two years of obtaining 25-OHD was collected. Associations between 25-OHD levels and acute vaso-occlusive events were analyzed by logistic regression. Odds ratios and 95% confidence intervals were calculated for the risk of pain and ACS associated with vitamin D deficiency (25-OHD <20 ng/ml). RESULTS: Subjects were 3-20 years old (median 10.6); 48 males, 47 females; 46 African, 49 Hispanic; 72 SS, 20 SC, 1 S/ß(0) Thalassemia, and 2 S/ß(+) Thalassemia. Median 25-OHD was 16 ng/ml. Fifty-six (59%) were vitamin D-deficient. Thirty-one (33%) and 29 (31%) had at least one episode of pain and ACS, respectively. Serum 25-OHD was significantly associated with pain (P = 0.0121) but not with ACS (P = 0.628). Of those with pain, 73% (23/31) were vitamin D-deficient while 26% (8/31) had 25-OHD ≥20 ng/ml (P = 0.04, OR = 2.7, 95%CI = 1.05-6.94). CONCLUSIONS: Our findings emphasize the high prevalence of vitamin D deficiency and its potential association with acute pain in SCD. Correcting low vitamin D may offer a simple, low-cost intervention to help reduce acute vaso-occlusive complications.

Regulatory B-cell compartment in transfused alloimmunized and non-alloimmunized patients with sickle cell disease.

Transfusion therapy is a life-sustaining treatment for patients with sickle cell disease (SCD), but can cause serious complications including alloimmunization. We previously reported diminished regulatory T cells (Tregs) and skewed Th2 responses in alloimmunized SCD patients. We hypothesized that the B cell regulatory (Breg) compartment, which controls Treg and Th differentiation, may also be compromised in allosensitized SCD patients. Phenotypically, we did not find differences in the frequency or numbers of CD24(hi) CD38(hi) and CD24(hi) CD27(+) B cell subsets, both previously identified as human Bregs, between alloimmunized and non-alloimmunized SCD patients on regular transfusions. However, at the functional level, CD19+ B cells from alloimmunized SCD patients expressed lower levels of IL-10 following stimulation as compared with non-alloimmunized patients (P < 0.05), and had reduced ability in inhibiting autologous CD14+ monocyte TNF-α expression (P < 0.05). These findings suggest that Bregs from alloimmunized and non-alloimmunized SCD patients differ in their ability to produce IL-10 and dampen monocyte activation, all consistent with an altered immunoregulatory state in alloimmunized SCD patients.

Medical management of tumors associated with Kasabach-Merritt phenomenon: an expert survey.

Kasabach-Merritt phenomenon (KMP) is a rare consumptive coagulopathy characterized by profound thrombocytopenia and hypofibrinogenemia occurring in association with the vascular tumors kaposiform hemangioendothelioma (KHE) and tufted angioma (TA). Treatment remains challenging without consensus on the optimal medical management. The authors compiled expert opinions regarding management to establish treatment recommendations. Twenty-seven vascular anomalies centers in the United States and Canada were surveyed using 2 representative cases of KHE/TA with and without KMP. Overall response rate was 92% (25/27) with 88% completion (24/27). Most sites (23/25; 92%) do not have a standard of practice for management. The most frequent initial therapy for KHE+KMP was a combination of systemic corticosteroids and vincristine (VCR) (12/24 centers; 50%) followed by corticosteroids alone (29%). Second-line treatments were VCR (38%), rapamycin (21%), and propranolol (21%). Management of KHE/TA without KMP was variable; initial treatments included systemic corticosteroids (8/24; 33%) alone or with VCR (9/24; 38%), monitoring without medication (33%), VCR (8%), propranolol (8%), aspirin (4%), and rapamycin (4%). This survey highlights certain trends in the management of KMP-associated tumors, without standard protocols and consensus.

Acute chest syndrome, airway inflammation and lung function in sickle cell disease.

BACKGROUND: Acute chest syndrome (ACS) is an acute complication in SCD but its effects on lung function are not well understood. Inflammation is a key component of SCD pathophysiology but with an unclear association with lung function. We hypothesized that children with ACS had worse lung function than children without ACS and aimed to investigate the association of lung function deficits with inflammatory cytokines. METHODS: Patients enrolled in a previous 2-year randomized clinical trial who had consented to future data use, were enrolled for the present exploratory study. Patients were categorized into ACS and non-ACS groups. Demographic and clinical information were collected. Serum samples were used for quantification of serum cytokines and leukotriene B4 levels and pulmonary function tests (PFTs) were assessed. RESULTS: Children with ACS had lower total lung capacity (TLC) at baseline and at 2 years, with a significant decline in forced expiratory volume in 1 sec (FEV1) and mid-maximal expiratory flow rate (FEF25-75%) in the 2 year period (p = 0.015 and p = 0.039 respectively). For children with ACS, serum cytokines IL-5, and IL-13 were higher at baseline and at 2 years compared to children with no ACS. IP-10 and IL-6 were negatively correlated with PFT markers. In multivariable regression using generalized estimating equation approach for factors predicting lung function, age was significantly associated FEV1 (p = 0.047) and ratio of FEV1 and forced vital capacity (FVC)- FEV1/FVC ratio (p = 0.006); males had lower FEV1/FVC (p = 0.035) and higher TLC (p = 0.031). Asthma status was associated with FEV1 (p = 0.017) and FVC (p = 0.022); history of ACS was significantly associated with TLC (p = 0.027). CONCLUSION: Pulmonary function abnormalities were more common and inflammatory markers were elevated in patients with ACS, compared with those without ACS. These findings suggest airway inflammation is present in children with SCD and ACS, which could be contributing to impaired pulmonary function.

Effects of chronic transfusions on abdominal sonographic abnormalities in children with sickle cell anemia.

OBJECTIVE: To assess the effects of chronic erythrocyte transfusions on prevalence of sonographic incidence of organ damage in children with sickle cell anemia (SCA). STUDY DESIGN: Children (N=148; mean age, 13.0 years) with SCA, receiving chronic transfusions (average, 7 years), underwent abdominal sonography at 25 institutions. After central imaging review, spleen, liver, and kidney measurements were compared with published normal values. Potential relations between ultrasound, clinical, and laboratory data were explored via analysis of variance, Student t test, and Cochran-Mantel-Haenzel tests of non-zero correlation. RESULTS: Average spleen length was similar to normal children, but over one-third had spleen volumes >300 mL, 15 had previous splenectomy for splenomegaly, and 24 had abnormal splenic echotexture. Two-thirds had hepatobiliary disease; 37 had prior cholecystectomy, 46 had gallstones, and 16 had gallbladder sludge. Gallbladder disease correlated with older age (P=.002), longer liver length (P<.001), longer duration of transfusions (P=.034), and higher total bilirubin (P<.001). Liver (P<.001) and renal lengths (P≤.005) were larger than published norms. CONCLUSIONS: In children with SCA, long-term transfusion therapy may not prevent development or progression of abdominal organ dysfunction.

Racial and ethnic differences in substance abuse treatment initiation and engagement.

This study examined variations by race and ethnicity in initiation and engagement, two performance measures of treatment for substance use disorders that focus on the timely receipt of services during the early stage of substance abuse treatment. Administrative data from the Oklahoma Department of Mental Health and Substance Abuse Services were linked with facility-level information from the National Survey of Substance Abuse Treatment Services. We found that Black clients were least likely to initiate treatment, but no race or ethnic differences in treatment engagement were found when compared by race or ethnicity. Most client and facility characteristics' association with initiation or engagement did not differ across racial or ethnic groups. Increased attention is needed to understand what may contribute to the differences and how to address them. This study also offers an approach that state agencies may implement for monitoring treatment quality and examining racial and ethnic disparities in substance abuse treatment services.

Serum ferritin level changes in children with sickle cell disease on chronic blood transfusion are nonlinear and are associated with iron load and liver injury.

Chronic blood transfusion is increasingly indicated in patients with sickle cell disease. Measuring resulting iron overload remains a challenge. Children without viral hepatitis enrolled in 2 trials for stroke prevention were examined for iron overload (STOP and STOP2; n = 271). Most received desferrioxamine chelation. Serum ferritin (SF) changes appeared nonlinear compared with prechelation estimated transfusion iron load (TIL) or with liver iron concentrations (LICs). Averaged correlation coefficient between SF and TIL (patients/observations, 26 of 164) was r = 0.70; between SF and LIC (patients/observations, 33 of 47) was r = 0.55. In mixed models, SF was associated with LIC (P = .006), alanine transaminase (P = .025), and weight (P = .026). Most patients with SF between 750 and 1500 ng/mL had a TIL between 25 and 100 mg/kg (72.8% +/- 5.9%; patients/observations, 24 of 50) or an LIC between 2.5 and 10 mg/g dry liver weight (75% +/- 0%; patients/observations, 8 of 9). Most patients with SF of 3000 ng/mL or greater had a TIL of 100 mg/kg or greater (95.3% +/- 6.7%; patients/observations, 7 of 16) or an LIC of 10 mg/g dry liver weight or greater (87.7% +/- 4.3%; patients/observations, 11 of 18). Although SF changes are nonlinear, levels less than 1500 ng/mL indicated mostly acceptable iron overload; levels of 3000 ng/mL or greater were specific for significant iron overload and were associated with liver injury. However, to determine accurately iron overload in patients with intermediately elevated SF levels, other methods are required. These trials are registered at www.clinicaltrials.gov as #NCT00000592 and #NCT00006182.

Immune regulation in chronically transfused allo-antibody responder and nonresponder patients with sickle cell disease and ß-thalassemia major.

Red blood cell alloimmunization is a major complication of transfusion therapy. Host immune markers that can predict antibody responders remain poorly described. As regulatory T cells (Tregs) play a role in alloimmunization in mouse models, we analyzed the Treg compartment of a cohort of chronically transfused patients with sickle cell disease (SCD, n = 22) and ß-thalassemia major (n = 8) with and without alloantibodies. We found reduced Treg activity in alloantibody responders compared with nonresponders as seen in mice. Higher circulating anti-inflammatory IL-10 levels and lower IFN-γ levels were detected in non-alloimmunized SCD patients. Stimulated sorted CD4+ cells from half of the alloimmunized patients had increased frequency of IL-4 expression compared with nonresponders, indicating a skewed T helper (Th) 2 humoral immune response in a subgroup of antibody responders. All patients had increased Th17 responses, suggesting an underlying inflammatory state. Although small, our study indicates an altered immunoregulatory state in alloantibody responders which may help future identification of potential molecular risk factors for alloimmunization.