Immunoglobulin prophylaxis prevents hospital admissions for fever in pediatric acute lymphoblastic leukemia: results of a multicenter randomized trial.

Infections lead to substantial morbidity during treatment of acute lymphoblastic leukemia (ALL) in which the adaptive immune system gets severely affected, leading to declining serum immunoglobulin levels. The aim of this trial was to investigate whether intravenous immunoglobulin (IVIG) prophylaxis in pediatric patients with ALL prevents admissions for fever. This randomized controlled trial was a subtrial of the national Dutch multicenter ALL study. Patients aged 1-19 years with medium risk (MR) ALL were randomized into two groups receiving either IVIG prophylaxis (0.7 g/kg IVIG given every three weeks, starting day 22 after diagnosis) or well defined standard of care (control group). Between October 2012 until March 2019, 91 (51%) patients were randomly assigned to IVIG prophylaxis and 86 (49%) to the control arm. In the IVIG prophylaxis group there were 206 admissions for fever versus 271 in the control group (p=0.011). IVIG prophylaxis was not associated with bacteremia. However, IVIG prophylaxis was associated with significantly less admissions for fever with negative blood cultures compared to the control group (N=113 versus 200, p.

Thrombocytopaenia: a serious side effect of diazoxide.

A 2.5-year-old boy with a history of (transient) congenital hyperinsulinism was admitted to the paediatric ward with recurrent hypoglycaemia. Diazoxide 5 mg/kg/day and hydrochlorothiazide 2 mg/kg/day were initiated. After increasing the dose of diazoxide to 10 mg/kg/day, the child developed mild rectal bleeding, petechiae, epistaxis and haematemesis. Blood screening showed severe thrombocytopaenia. Diazoxide and hydrochlorothiazide were stopped, and his platelet count normalised. Drug rechallenge was positive. Drug-induced immune thrombocytopaenia was diagnosed.

Exploratory Study of Predicted Indirectly ReCognizable HLA Epitopes in Mismatched Hematopoietic Cell Transplantations.

HLA-mismatches in hematopoietic stem-cell transplantation are associated with an impaired overall survival (OS). The aim of this study is to explore whether the Predicted Indirectly ReCognizable HLA-Epitopes (PIRCHE) algorithm can be used to identify HLA-mismatches that are related to an impaired transplant outcome. PIRCHE are computationally predicted peptides derived from the patient's mismatched-HLA molecules that can be presented by donor-patient shared HLA. We retrospectively scored PIRCHE numbers either presented on HLA class-I (PIRCHE-I) or class-II (PIRCHE-II) for a Dutch multicenter cohort of 103 patients who received a single HLA-mismatched (9/10) unrelated donor transplant in an early phase of their disease. These patients were divided into low and high PIRCHE-I and PIRCHE-II groups, based on their PIRCHE scores, and compared using multivariate statistical analysis methods. The high PIRCHE-II group had a significantly impaired OS compared to the low PIRCHE-II group and the 10/10 reference group (HR: 1.86, 95%-CI: 1.02-3.40; and HR: 2.65, 95%-CI: 1.53-4.60, respectively). Overall, PIRCHE-II seem to have a more prominent effect on OS than PIRCHE-I. This impaired OS is probably due to an increased risk for severe acute graft-vs.-host disease. These data suggest that high PIRCHE-II scores may be used to identify non-permissible HLA mismatches within single HLA-mismatched hematopoietic stem-cell transplantations.

[A neonate with rectal bleeding]. / Een pasgeborene met rectaal bloedverlies.

BACKGROUND: Rectal bleeding in neonates is commonly associated with non-significant anal fissures or with the severe condition necrotising enterocolitis (NEC). A 'banal' bacterial colitis is often considered unlikely and, subsequently, diagnostics for this condition are usually not conducted. CASE DESCRIPTION: We describe the case of an otherwise healthy neonate who experienced rectal blood loss as a result of Campylobacterjejuni infection. CONCLUSION: The diagnosis 'infectious colitis' should be considered in cases of rectal bleeding in neonates. Antibiotic treatment for Campylobacter infection is advised for children under the age of three months, since the risk of a fulminant disease trajectory is high in this patient group.

Predicted Indirectly ReCognizable HLA Epitopes Class I Promote Antileukemia Responses after Cord Blood Transplantation: Indications for a Potential Novel Donor Selection Tool.

Unrelated cord blood transplantation (UCBT) provides a curative therapy for patients with hematological malignancies. The effect of HLA mismatches in UCBT is currently the subject of debate. HLA-mismatched UCBT may lead to improved leukemia control but also to graft-versus-host disease (GVHD), resulting in nonrelapse mortality (NRM). The aim of this study was to investigate whether indirect recognition of mismatched HLA provides an explanation for the graft-versus-tumor effect and risk of GVHD. The probability of indirect recognition was predicted by the Predicted Indirectly ReCognizable HLA Epitopes (PIRCHE) model. The effect of the numbers of PIRCHE presented on HLA class I and II (PIRCHE-I and -II) was studied in 134 pediatric patients. To study the effects of higher numbers of PIRCHE, patients were divided in 2 equally sized groups, using the median number of PIRCHE as cutoff values. Proportional hazard models and competing risk analyses were performed to study the effect of PIRCHE on the clinical outcomes relapse, acute and chronic GVHD, NRM, and disease-free and overall survival. Above median PIRCHE-I were associated with reduced relapse risk (HR, .26; 95% CI, .07 to .94; P = .04), evaluating the 50 patients transplanted for a malignancy. Both PIRCHE-I and -II were not associated with other clinical outcomes, including GVHD and NRM. These data suggest that high PIRCHE-I may lead to improved graft-versus-tumor effects after UCBT, without an accompanying GVHD risk. Inclusion of PIRCHE in UCB selection criteria may enhance UCBT outcome, which needs to be tested in prospective studies.

The number of T cell allo-epitopes associates with CD4+ and CD8+ T-cell infiltration in pediatric cutaneous GVHD.

Risk factors for graft-versus-host disease (GVHD) following allogeneic hematopoietic stem-cell transplantation (HCST) include: HLA mismatches, sex-mismatch, and stem-cell source. We retrospectively analyzed if HLA- and sex-mismatching quantitatively affects the composition of GVHD-induced T-cell infiltrates. We quantified absolute numbers of CD4+ and CD8+ T cells present in tissue sections from skin biopsies of 23 pediatric HSCT-recipients with GVHD. HSCT with a sex-mismatched unrelated donor was associated with an increased number of CD4+ T cells when compared to a sex-matched unrelated donor (p=0.01). The absolute numbers of skin-infiltrating T cells were increased in patients expressing T-cell epitopes derived from the recipient's mismatched HLA, so called predicted indirectly recognizable HLA epitopes (PIRCHE). The combined expression of PIRCHE with a sex-mismatch resulted in the highest number of skin-infiltrating T cells. Our results indicate that an increased number of recipient-specific T-cell epitopes is associated with accumulation of CD4+ and CD8+ T cells in the skin.

Refinement of the definition of permissible HLA-DPB1 mismatches with predicted indirectly recognizable HLA-DPB1 epitopes.

Hematopoietic stem cell transplantation with HLA-DPB1-mismatched donors leads to an increased risk of acute graft-versus-host disease (GVHD). Studies have indicated a prognostic value for classifying HLA-DPB1 mismatches based on T cell-epitope (TCE) groups. The aim of this study was to determine the contribution of indirect recognition of HLA-DP-derived epitopes, as determined with the Predicted Indirectly ReCognizable HLA Epitopes (PIRCHE) method. We therefore conducted a retrospective single-center analysis on 80 patients transplanted with a 10/10 matched unrelated donor that was HLA-DPB1 mismatched. HLA-DPB1 mismatches that were classified as GVH nonpermissive by the TCE algorithm correlated to higher numbers of HLA class I as well as HLA class II presented PIRCHE (PIRCHE-I and -II) compared with permissive or host-versus-graft nonpermissive mismatches. Patients with acute GVHD grades II to IV presented significantly higher numbers of PIRCHE-I compared with patients without acute GVHD (P < .05). Patients were divided into 2 groups based on the presence or absence of PIRCHE. Patients with PIRCHE-I or -II have an increased hazard of acute GVHD when compared with patients without PIRCHE-I or -II (hazard ratio [HR], 3.19; 95% confidence interval [CI], 1.10 to 9.19; P < .05; and HR, 4.07; 95% CI, .97 to 17.19; P = .06, respectively). Patients classified as having an HLA-DPB1 permissive mismatch by the TCE model had an increased risk of acute GVHD when comparing presence of PIRCHE-I with absence of PIRCHE-I (HR, 2.96; 95% CI, .84 to 10.39; P = .09). We therefore conclude that the data presented in this study describe an attractive and feasible possibility to better select permissible HLA-DPB1 mismatches by including both a direct and an indirect recognition model.

Indirectly Recognized HLA-C Mismatches and Their Potential Role in Transplant Outcome.

HLA-C mismatches are clearly associated to alloreactivity after hematopoietic stem-cell transplantation; in a number of large cohorts, HLA-C mismatches are correlated to an increased risk of acute graft-versus-host disease (GVHD) or even impaired survival. While for HLA-A and -B, both antigenic as well as allelic mismatches are associated with an increased risk of acute GVHD, such an increased risk is only observed for antigenic HLA-C mismatches and not for allelic mismatches. These observations raise the question what sets HLA-C apart from HLA-A and -B. The difference may well be related to the reduced levels of cell-surface expression of HLA-C as compared to HLA-A and -B, possibly due to, among other factors, a limited peptide-binding capacity. This limited peptide-binding capacity may retain HLA-C in the ER and enhance degradation of the HLA-C protein. Once degraded, HLA-C-derived peptides can be presented to the immune system via other HLA alleles and are thus available for indirect recognition. Indeed, such HLA-C-derived peptides have previously been eluted from other HLA alleles. We have recently developed an approach to predict indirect recognition of HLA molecules, by establishing the numbers of predicted indirectly recognizable HLA epitopes (PIRCHES). The number of PIRCHES presented on HLA class I and II (PIRCHE-I and -II, respectively), are highly correlated to clinical measures of alloreactivity, such as acute GVHD. In the present "Hypothesis & Theory," we reviewed the current knowledge on HLA-C mismatches and alloreactivity. Moreover, we speculate about the role of direct and indirect recognition of HLA-C and the consequences for donor selection in HLA-C mismatched stem-cell transplantation.

Complete donor chimerism is a prerequisite for the effect of Predicted Indirectly ReCognizable HLA Epitopes (PIRCHE) on acute graft-versus-host disease.

Predicted indirectly recognizable HLA epitopes (PIRCHE) computationally predict donor T-cell recognition of mismatched-HLA derived peptides following allogeneic haematopoietic stem-cell transplantation (allo-HSCT), as is evidenced by the correlation between presence of HLA-DPB1-derived PIRCHE and the occurrence of graft-vs.-host disease (GVHD). Complete donor T-cell chimerism associates with an increased GVHD risk compared to mixed patient and donor chimerism. If the correlation between the presence of PIRCHE and GVHD occurrence is indeed mediated by donor T cells, the presence of donor T cells should be required to observe such a correlation. This study was initiated to investigate whether the effect of PIRCHE is different in patients with complete chimerism compared to those with mixed chimerism. Indeed, the correlation between PIRCHE and GVHD is present in patients with complete chimerism, whereas it is absent in those with mixed chimerism. The data presented here suggest that chimerism status is important for the detection of potential GVHD epitopes.