The pathogenesis of chronic spontaneous urticaria (CSU) is still insufficiently understood. Recent findings suggest that immunoglobulins, in particular IgE but also IgA, play a role in the development of CSU.
Our aim was to assess differences in clinical and laboratory markers between CSU patients with and without lower levels of serum IgA and IgE.
We analyzed the data of 606 patients with CSU by dividing them into four groups based on their IgA and IgE levels. The groups were compared for their spectrum of symptoms, disease activity, concomitant autoimmunity and routine laboratory markers. Autoreactivity was assessed by basophil activation test (BAT). Moreover, IgE-anti-thyroid peroxidase (TPO) was measured.
Of the patients with lower IgE levels, 66.5% also had lower IgA levels (r=0.316, p<0.001). Patients with lower IgA and lower IgE levels showed a higher prevalence of recurrent angioedema (p=0.03, p=0.04) and concomitant autoimmunity (p=0.006, p<0.001). Autoreactivity was also found more frequently in patients with lower IgA and lower IgE levels (p=0.003, p<0.001). Reduced basophil counts were linked to both, lower IgA and lower IgE levels (p<0.001), whereas low eosinophil counts were primarily present in patients with lower IgE levels (p=0.04, p<0.001). Patients with elevated IgE-anti-TPO levels had lower IgA (p=0.007) and IgE levels (p=0.001).
Lower IgA levels in CSU are linked to lower IgE levels and features of autoimmune urticaria. Our findings encourage to screen CSU patients for serum IgA and IgE levels and to further assess their role as disease biomarkers.
Copyright © 2021 Sauer, Scheffel, Frischbutter, Kolkhir, Xiang, Siebenhaar, Altrichter, Maurer, Metz and Krause.

CD83 is known to regulate lymphocyte maturation, activation, homeostasis, and antibody response to immunization and infection. While CD83 has a major part in B cell function, its role in influenza A virus infection has not yet been investigated.
We investigated the role of CD83 using C57BL/6J wild type mice and CD83 knockout (KO) mice after intraperitoneal administration of the influenza A/WSN/1933 virus. We analyzed cells of the peritoneal cavity, splenocytes, and cells of the bone marrow with FACS to investigate CD83 expression and cell population change in response to the virus infection. ELISA was performed with sera and peritoneal cavity fluids to detect A/WSN/1933 virus-specific IgG and the subclasses of IgG.
FACS analysis data showed a transient but distinct induction of CD83 expression in the peritoneal B cells of wild type mice. CD83 KO mice exhibited a delayed recovery of B cells in the bone marrow after influenza virus infection and overall, a smaller T cell population compared to wild type mice. The peritoneal cavity and serum of the wild type mice contained a high titer of IgG within 14 days after infection, whereas the CD83 KO mice had a very low titer of IgG.
These results show the importance of CD83 in lymphocytes homeostasis and antibody production during influenza A virus infection.

Background Flowcytometric identification of basophils is a prerequisite for measuring activation of basophils with IgE-dependent or IgE-independent stimuli. Aim of this study was to compare different marker combinations in a simultaneous multicolor flowcytometric measurement. Methods Ten patients with a grass pollen allergy and 3 controls were included in the study. Basophilic cells were gated by using anti-CCR3647, anti-IgE, anti-CRTH2, anti-CD203c und anti-CD3. Cells were activated by a monoclonal anti-FcεRI antibody, N-formyl-methionyl-leucyl-phenylalanine (fMLP) and the allergen extract Phleum pratense. The activation marker anti-CD63 was used. Results The highest relative number of basophils was found with anti-CCR3+ cells, anti-IgE+ and anti-IgE+ /anti-CD203c+ cells, the lowest with CRTH2+ /CD203c+ /CD3- cells. A very good and good concordance of CCR3+ cells was seen with CCR3+ /CD3- cells and CRTH2+ /CD203c+ /CD3- cells in all experiments. The contamination of the CCR3+ population with CD3+ cells and the contamination of the IgE+ -population with CCR3- cells and CD203- cells were the lowest compared to all other marker combinations. Conclusions As the highest relative number of basophils was identified by anti-CD193 (CCR3) followed by the anti-IgE and anti-IgE/antiCD203c positive population in most cases, these markers can generally be recommended for identification of basophils. If a basophil population with very high purity is needed, anti-IgE should be chosen. © 2014 Clinical Cytometry Society.
Copyright © 2014 Clinical Cytometry Society.