The immunoreceptor adapter protein DAP12 suppresses B lymphocyte–driven adaptive immune responses

Human and mouse B cells lacking functional DAP12 are hyperresponsive, and DAP12 works with MAIR-II (CD300d) to negatively regulate B cell activity

Five‐year histological and serological follow‐up of operationally tolerant pediatric liver transplant recipients enrolled in WISP‐R

Pediatric liver transplant recipients arguably have the most to gain and the most to lose from discontinuing immunosuppression (IS). While IS undoubtedly exerts a cumulative toll, there is concern that insufficient or no IS may contribute to allograft deterioration. Twelve pediatric recipients of parental living donor liver grafts, identified as operationally tolerant through complete IS withdrawal (WISP-R; NCT00320606) were followed for a total of five years (one year of IS withdrawal and four years off IS) with serial liver tests, auto- and allo-antibody assessments. Liver biopsies were performed two and four years off IS and, at these time points, immunoglobulin G (IgG) subclass and C1q binding activity for donor specific antibodies (DSAs) were determined. There were no cases of chronic rejection, graft loss, or death. Allografts did not exhibit progressive increase in inflammation or fibrosis. Smooth muscle actin (SMA) expression by stellate cells and CD34 expression by liver sinusoidal endothelial cells (LSECs) remained stable, consistent with the absence of progressive graft injury. Three subjects never exhibited DSA. However, three subjects showed intermittent de novo Class I DSA, four subjects showed persistent de novo Class II DSA and five subjects showed persistent pre-existing Class II DSA. Class II DSA was predominantly against donor DQ antigens, often of high mean fluorescence intensity (MFI), rarely of the IgG3 subclass, and often capable of binding C1q. CONCLUSION: Operationally tolerant pediatric liver transplant recipients maintain generally stable allograft histology in spite of apparently active humoral allo-immune responses. The absence of increased inflammation or progressive fibrosis suggests that a subset of liver allografts seem resistant to the chronic injury that is characteristic of antibody-mediated damage

Association of Serum Calprotectin (S100A8/A9) Level With Disease Relapse in Proteinase 3-Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

Objective S100A8/A9 (calprotectin) has shown promise as a biomarker for predicting relapse in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). This study was undertaken to investigate serum S100A8/A9 level as a biomarker for predicting future relapse in a large cohort of patients with severe AAV. Methods Serum levels of S100A8/A9 were measured at baseline and months 1, 2, and 6 following treatment initiation in 144 patients in the Rituximab in ANCA-Associated Vasculitis trial (cyclophosphamide/azathioprine versus rituximab [RTX] for induction of remission) in whom complete remission was attained. Results Patients were divided into 4 groups: proteinase 3 (PR3)-ANCA with relapse (n=37), PR3-ANCA without relapse (n=56), myeloperoxidase (MPO)-ANCA with relapse (n=6), and MPO-ANCA without relapse (n=45). Serum S100A8/A9 level decreased in all groups during the first 6 months of treatment. The percentage reduction from baseline to month 2 was significantly different between patients who experienced a relapse and those who did not in the PR3-ANCA group (P=0.046). A significantly higher risk of relapse was associated with an increase in S100A8/A9 level between baseline and month 2 (P=0.0043) and baseline and month 6 (P=0.0029). Subgroup analysis demonstrated that patients treated with RTX who had increased levels of S100A8/A9 were at greatest risk of future relapse (P=0.028). Conclusion An increase in serum S100A8/A9 level by month 2 or 6 compared to baseline identifies a subgroup of PR3-ANCA patients treated with RTX who are at higher risk of relapse by 18 months. Since RTX is increasingly used for remission induction in PR3-ANCA-positive patients experiencing a relapse, S100A8/A9 level may assist in identifying those patients requiring more intensive or prolonged treatment

Rituximab Versus Cyclophosphamide for ANCA-Associated Vasculitis with Renal Involvement

Rituximab (RTX) is non-inferior to cyclophosphamide (CYC) followed by azathioprine (AZA) for remission-induction in severe ANCA-associated vasculitis (AAV), but renal outcomes are unknown. This is a post hoc analysis of patients enrolled in the Rituximab for ANCA-Associated Vasculitis (RAVE) Trial who had renal involvement (biopsy proven pauci-immune GN, red blood cell casts in the urine, and/or a rise in serum creatinine concentration attributed to vasculitis). Remission-induction regimens were RTX at 375 mg/m(2) x 4 or CYC at 2 mg/kg/d. CYC was replaced by AZA (2 mg/kg/d) after 3-6 months. Both groups received glucocorticoids. Complete remission (CR) was defined as Birmingham Vasculitis Activity Score/Wegener's Granulomatosis (BVAS/WG)=0 off prednisone. Fifty-two percent (102 of 197) of the patients had renal involvement at entry. Of these patients, 51 were randomized to RTX, and 51 to CYC/AZA. Mean eGFR was lower in the RTX group (41 versus 50 ml/min per 1.73 m(2); P=0.05); 61% and 75% of patients treated with RTX and 63% and 76% of patients treated with CYC/AZA achieved CR by 6 and 18 months, respectively. No differences in remission rates or increases in eGFR at 18 months were evident when analysis was stratified by ANCA type, AAV diagnosis (granulomatosis with polyangiitis versus microscopic polyangiitis), or new diagnosis (versus relapsing disease) at entry. There were no differences between treatment groups in relapses at 6, 12, or 18 months. No differences in adverse events were observed. In conclusion, patients with AAV and renal involvement respond similarly to remission induction with RTX plus glucocorticoids or CYC plus glucocorticoids

Clinical outcomes of treatment of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis based on ANCA type

Objective To evaluate whether the classification of patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) according to ANCA type (anti-proteinase 3 (PR3) or anti-myeloperoxidase (MPO) antibodies) predicts treatment response. Methods Treatment responses were assessed among patients enrolled in the Rituximab in ANCA-associated Vasculitis trial according to both AAV diagnosis (granulomatosis with polyangiitis (GPA)/microscopic polyangiitis (MPA)) and ANCA type (PR3-AAV/MPO-AAV). Complete remission (CR) was defined as disease activity score of 0 and successful completion of the prednisone taper. Results PR3-AAV patients treated with rituximab (RTX) achieved CR at 6 months more frequently than did those randomised to cyclophosphamide (CYC)/azathioprine (AZA) (65% vs 48%; p=0.04). The OR for CR at 6 months among PR3-AAV patients treated with RTX as opposed to CYC/AZA was 2.11 (95% CI 1.04 to 4.30) in analyses adjusted for age, sex and new-onset versus relapsing disease at baseline. PR3-AAV patients with relapsing disease achieved CR more often following RTX treatment at 6 months (OR 3.57; 95% CI 1.43 to 8.93), 12 months (OR 4.32; 95% CI 1.53 to 12.15) and 18 months (OR 3.06; 95% CI 1.05 to 8.97). No association between treatment and CR was observed in the MPO-AAV patient subset or in groups divided according to AAV diagnosis. Conclusions Patients with PR3-AAV respond better to RTX than to CYC/AZA. An ANCA type-based classification may guide immunosuppression in AAV

Factors Determining the Clinical Utility of Serial Measurements of Antineutrophil Cytoplasmic Antibodies Targeting Proteinase 3

Objective. Relapse following remission is common in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), particularly with ANCAs directed at proteinase 3 (PR3). This study was undertaken to evaluate the association of an increase in PR3-ANCA level with subsequent relapse. Methods. Data from the Rituximab versus Cyclophosphamide for ANCA-Associated Vasculitis (RAVE) trial were used. Starting from the time of achieving complete remission, serialmeasurements by direct and capture enzyme-linked immunosorbent assays (ELISAs) were analyzed in 93 patients with PR3-ANCA, using Cox proportional hazards regression. Results. An increase in PR3-ANCA level was identified in 58 of 93 subjects (62.4%) by direct ELISA and in 59 of 93 (63.4%) by capture ELISA. Relapses occurred in 55 of 93 subjects (59.1%), with 25 and 21 occurring within 1 year after an increase by direct ELISA and capture ELISA, respectively. An increase by direct ELISA was associated with subsequent severe relapses (hazard ratio [HR] 4.57; P <0.001), particularly in patients presenting with renal involvement (HR 7.94; P <0.001) and alveolar hemorrhage (HR 24.19; P <0.001). Both assays identified increased risk for severe relapse in the rituximab group (HR 5.80; P50.002 for direct ELISA andHR 4.54; P50.007 for capture ELISA) but not the cyclophosphamide/azathioprine group (P=0.103 and P=0.197, respectively). Conclusion. The association of an increase in PR3-ANCA level with the risk of subsequent relapse is partially affected by the PR3-ANCA detection methodology, disease phenotype, and remission induction treatment. An increase in PR3-ANCA level during complete remission conveys an increased risk of relapse, particularly severe relapse, among patients with renal involvement or alveolar hemorrhage and those treated with rituximab. Serial measurements of PR3-ANCA may be informative in this subset of patients, but the risk of relapse must be weighed carefully against the risks associated with therapy