Unexpected reactions of the anti-IgA antibody particle gel immunoassay.

BACKGROUND: The cause of allergic transfusion reactions remains often unknown, but in rare cases anti-immunoglobulin A (IgA) antibodies in patients with IgA-deficiency can be found. We report on the use of the DiaMed particle gel immunoassay (PaGIA) for detection of anti-IgA antibodies in patients with allergic transfusion reactions. METHODS: The examination of the suspected adverse reactions included an anti-IgA antibody test (ID-PaGIA Anti-IgA antibody test; DiaMed GmbH, Cressier , Switzerland) and measurement of IgA concentration in the patient's plasma. In the case of a discrepancy IgA subclasses were examined and neutralization of the anti-IgA antibodies by pure IgA was performed. RESULTS: Of 142 patients tested for IgA concentration and anti-IgA antibodies, 8 gave positive results for the anti-IgA antibody test. In seven of these cases (4.9% of the patients tested) IgA levels were found to be normal, and in four of five so tested, the positive result could not be neutralized with purified IgA. Only one patient had confirmed IgA deficiency with anti-IgA antibodies that were neutralized by addition of purified IgA. CONCLUSION: Cause and clinical relevance of a positive reaction of the anti-IgA antibody test in patients with normal total IgA and normal IgA subclasses remains unknown. Because of the high false positive rate we do not recommend this test as a screening test for anti-IgA antibodies when evaluating allergic transfusion reactions, but instead recommend measurement of total IgA in patient's plasma or serum as a primary screen for IgA deficiency with antibodies as a cause of allergic transfusion reaction.

Reduced blood leukocyte and neutrophil numbers in the pathogenesis of type 1 diabetes.

Very little is known about the role of the innate immune system in the course of human type 1 diabetes. Here we investigated neutrophil numbers along with other leukocyte populations in patients at diagnosis of type 1 diabetes and during prediabetes. Complete and differential blood counts were analyzed from 107 adult patients with newly diagnosed type 1 diabetes, 21 children with persistent islet autoantibodies and a family history of type 1 diabetes, and 1 238 age and gender matched control subjects, all individuals without any signs of acute infection.Adult patients with newly diagnosed type 1 diabetes had significantly lower total WBC (p<1×10⁻6), neutrophil (p<1×10⁻6), basophil (p<1×10⁻6), monocyte (p=4×10⁻6) and lymphocyte (p<1×10⁻6) counts compared to control subjects. Erythrocyte, eosinophil and platelet counts did not differ between groups. Similarly, children with persistent islet autoantibodies had decreased WBC (p=0.001), neutrophils (p=0.003), and lymphocytes (p=0.006) in comparison to control children. Our findings demonstrate a perturbation of leukocyte homeostasis at and prior to onset of type 1 diabetes suggesting a general involvement of the innate immune system in the pathogenesis of type 1 diabetes.

[SARS-CoV-2 antibodies in ICU and clinic staff : From Germany's region with the highest infection rate]. / SARS-CoV-2-Antikörper bei Intensiv- und Klinikpersonal : Aus der am höchsten durchseuchten Region Deutschlands.

BACKGROUND: Healthcare workers are a high-risk population for SARS-CoV­2 infection. For capacity planning of healthcare providers and to optimize protection of healthcare workers (HCW) in SARS-CoV­2 pandemics, it is essential to know the risk of infection and potential immunity status of staff dealing with COVID-19 patients. MATERIALS AND METHODS: We examined seropravalence of SARS-CoV­2 IgM/IgG antibodies (AB) in HCW of a region with the highest rate of infection (1570/100,000) during COVID-19 pandemic in Germany, 4 months after its start. Employees of a nonmedical company (MU) served as control group. Demographic data, medical history and working situation were recorded. RESULTS: A total of 1838 HCW and 986 MU volunteered to participate. Seroprevalence for SARS-CoV­2 in HCW was 15.1% and 3.7% in MU. Among HCWs, nurses had a seropositivity of 20.0%, ICU personnel 20.3%, housekeepers 19.3%, physicians 12.0%, medical services (e.g., radiology, physiotherapy) 11.3%, administration 7.1% and technical services 6%. Symptoms typical for COVID-19 were not experienced by 10% of seropositive HCWs. CONCLUSION: Seroprevalence of SARS-CoV­2 antibodies in HCW of a region heavily affected by COVID-19 is with 15.1% significantly higher than in a control group of nonmedical staff with 3.7%. Infection rate in HCW was higher in staff with close contact to infected patients. Seropositivity in ICU personnel is higher than in other clinical professions. The occupational risk for housekeepers seems to be underestimated.