Chronic immune thrombocytopenic purpura (ITP) is due to platelet destruction by an IgG antiplatelet antibody. Recent studies by some investigators suggest in vivo fixation of C3 by the antiplatelet antibody in ITP patients; other groups have not confirmed these findings. In the present studies, purified IgG produced in vitro by splenic cells from two patients with ITP resulted in C3 fixation to target platelets. Since cell-bound C3 increases the efficiency of cell destruction in many experimental antibody systems, the ability of the IgG antibody in patients with ITP to fix C3 may influence the severity of their disease.

BackgroundKawasaki disease (KD), the leading cause of acquired heart disease in children, primarily affects infants and toddlers. Investigations on immune responses during KD are hampered by a limited understanding of normal immune responses in these ages. It’s well known that Infants have poorer vaccine responses and difficulty with maintaining prolonged serum immunity, but there are few studies on human infants detailing immune deficiencies. Limited studies propose an inability to maintain life-long bone marrow plasma cells. Plasmablasts are a transitional cell form of B cells that lead to long-term Plasma cells. Plasmablasts levels rise in the peripheral blood after exposure to a foreign antigen. In adult studies, these responses are both temporally and functionally well characterized. To date, there have been few studies on plasmablasts in the predominant age range of KD.MethodsChildren presenting to an urban pediatric emergency room undergoing laboratory evaluation, who had concern of KD or had fever and symptoms overlapping those of KD, were recruited. Peripheral blood mononuclear cells were isolated and evaluated utilizing flow cytometry with specific B cell markers from 18 KD subjects and 69 febrile controls.ResultsPlasmablast numbers and temporal formation are similar between infectious disease controls and KD subjects. In both groups, infants have diminished plasmablast responses compared to older children.ConclusionIn this single-time point survey, infants have a blunted peripheral plasmablast response. Overall, similar plasmablast responses in KD and controls support an infectious disease relationship to KD. Future time-course studies of plasmablasts in infants are warranted as this phenomenon may contribute to observed immune responses in this age group.

BackgroundKawasaki disease (KD) is a febrile childhood vasculitis of unknown etiology. The diagnosis is highly concerning as over a quarter of children who fail to receive timely treatment with intravenous immunoglobulin (IVIG) will develop coronary aneurysms. Diagnosis relies on proper symptomatology and is supported by non-specific markers of inflammation. Previous studies have identified elevated plasma levels of interleukin-21 (IL-21) as a sensitive and specific biomarker in KD. The aim of this study is to assess the validity of IL-21 as a diagnostic biomarker for KD in febrile children in North America.MethodsPlasma samples were collected from children who presented to an urban Emergency Department in North America. IL-21 levels were measured using commercial ELISA kits in 12 KD versus 60 controls subjects.ResultsOur study shows that IL-21 levels were non-specifically elevated across all febrile children, irrespective of KD diagnosis. Length of fever prior to sample collection does not correlate with IL-21 levels. Other inflammatory markers and laboratory values were also compared to IL-21 and show no significant correlation.ConclusionsSince IL-21 is elevated non-specifically in this cohort, our data supports that IL-21 is not an appropriate biomarker for diagnosis of KD in North American pediatric populations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12969-017-0163-3) contains supplementary material, which is available to authorized users.

Severe Hypocalcemia and Acute Respiratory Failure in a 3-Month-old Boy With ConstipationT o the Editor: We present a case highlighting how insufficient parental anticipatory guidance regarding administration of common over the counter laxatives may cause serious harm. A 3month-old boy with constipation presented to our emergency department with respiratory distress, lethargy, and emesis. The patient had metabolic acidosis (pH 7.2, CO 2 17, base deficit À6, anion gap 3), lactic acidosis (5.5 mmol/L), hypernatremia (156 mEq/L), hypokalemia (2.3 mEq/L), hypocalcemia (3.5 mg/dL), and hyperphosphatemia (9.6 mg/dL). He became apneic requiring endotracheal intubation. Brain computerized tomography scan revealed an aging germinal matrix hemorrhage without acute pathology.Our differential diagnosis included severe sepsis, inborn error of metabolism, impaired renal function, malabsorption, pancreatitis, tumor lysis, rhabdomyolysis, or unintentional intoxication. Days later, upon detailed questioning, the patient's father recalled administering Fleet enemas for constipation but unintentionally gave them orally. Ultimately, enteral uptake of exogenous phosphate caused systemic toxicity producing the presentation above. Reported cases of laxative-induced tetany are frequently noted in children with comorbid nephropathy or colonic dysmotility ( 1). Yet, a third are described in healthy children treated for constipation (1-4). After intravenous supplementation, our patient's metabolic derangements were corrected. He was extubated and 1 week later was discharged home without sequelae.Explicit anticipatory guidance for common over-the-counter medications is paramount. Providers must counsel families to administer laxatives as directed including dose, volume, route, and frequency. Caregivers should be given opportunities to vocalize understanding and provide simulated administration. Finally, abnormal laboratory data must be confirmed, assessed in clinical context, and with anticipation of potential sequelae that if untreated may be fatal.