Influenza A virus enhances basophil histamine release and the enhancement is abolished by carbohydrates

Continuous tracking of COVID-19 patients' immune status

•

The immune status of COVID-19 patients is different in each stage.

•

DN and DP cells are negatively correlated with IL-10 and IL-6, respectively.

•

Immune indexes help to distinguish COVID-19 and its severity early.

•

Dynamic immune monitoring can provide a reference for clinical drug selection.

Background

COVID-19 is threating human health worldwide. We aim to investigate the dynamic changes of immune status in COVID-19 patients with clinical evolution.

Methods

Sixty-one COVID-19 patients (42 mild cases and 19 severe cases, 51 cases without secondary infection as non-infection group and 10 cases with secondary bacterial/fungal infection as infection group) and 52 healthy controls (HCs) were enrolled from our hospital. Leucocyte classification, lymphocyte subsets and cytokines were detected by full-automatic blood cell analyzer and flow cytometer, respectively.

Results

Upon admission, eosinophils and lymphocyte subsets decreased significantly, while neutrophils, monocytes, basophils, IL-2, IL-6, IL-10 and IFN-γ increased significantly in COVID-19 patients compared to HCs. CD3⁺ T and DN (CD3⁺CD4⁻CD8⁻) cells appeared sustained decline, leucocytes, neutrophils and IL-10 showed sustained increase in severe group compared to mild group. Compared with the non-infection group, we observed a depletion of eosinophils, CD3⁺ T and CD4⁺ T cells, but leucocytes, neutrophils, IL-6 and IL-10 on the contrary in the infection group. Besides, in severe group of COVID-19 patients, DN cells were negatively correlated with IL-10, and DP (CD3⁺CD4⁺CD8⁺) cells were negatively correlated with IL-6. Lymphocytes, eosinophils, CD3⁺ T cells, CD4⁺ T cells, IL-6 and IL-10 all had great diagnostic efficacy (AUC, 0.905-0.975) for COVID-19. The laboratory indicators of COVID-19 patients with improved condition also showed a recovery trend with time.

Conclusions

The immune status of COVID-19 patients is different in each stage, and dynamic monitoring of related indicators can help predict the disease and may avoid cytokine storms.

Allergen-specific immunotherapy: is it vaccination against toxins after all?

IgE-mediated allergies, in particular allergic rhinoconjunctivitis and asthma, have reached epidemic proportions, affecting about one-third of the population in developed countries. The most effective treatment for allergies is specific immunotherapy (SIT), which involves the injection of increasing doses of an allergen extract to allergic individuals. The current form of SIT was first introduced in 1911 and recently celebrated its 100th birthday for the treatment of hay fever. The concept of this therapy at the time was straightforward, as it was believed that pollen contained toxins against which the patient could be vaccinated. However, the understanding became blurred with the discovery that IgE antibodies were the effector molecules of the allergic response. Subsequent research focused on the idea that SIT should induce tolerance keeping the IgE antibodies at bay. In this review, we will discuss the various hypotheses for the mechanism of SIT and we will put forward the concept that allergens may be viewed as 'protoxins' which need to be activated by IgE antibodies. Within this framework, protoxin-neutralizing antibodies are the key effector molecules while a shift to Th1 or Treg cells mainly contributes to the efficacy of SIT by helping B cells to produce neutralizing IgG antibodies.

Infection with influenza a virus leads to flu antigen-induced cutaneous anaphylaxis in mice

It is well established, that viral infections may trigger urticaria or allergic asthma; however, as viral infections induce T helper 1 polarized responses, which lead to the inhibition of T helper 2 cell development, the opposite would be plausible. We wanted to investigate how viral infections may mediate allergic symptoms in a mouse model; therefore, we infected BALB/C mice with influenza A virus intranasally. Histologic analyses of lung sections and bronchoalveolar lavages were performed. In addition, cells from the mediastinal lymph nodes were restimulated in vitro to analyze which types of cytokines were induced by the flu infection. Furthermore, flu-specific antibody titers were determined and local anaphylaxis was measured after rechallenge with flu antigen. We found that airways inflammation consisted predominately of macrophages and lymphocytes, whereas only a few eosinophils were observed. interferon-gamma but no interleukin-4 and little interleukin-5 could be detected in the culture supernatants from in vitro restimulated T cells from the draining lymph nodes. The antibody response was characterized by high levels of virus-specific IgG2a, IgG2b, and IgG1 and, surprisingly, low levels of virus-specific IgE antibodies. Interestingly, flu-infected mice developed active and passive cutaneous anaphylaxis after rechallenge with flu-antigen. As the passive cutaneous anaphylaxis reaction persisted over 48 h and was significantly lower after passive transfer of the serum, which was IgE depleted, local anaphylaxis seemed to be mediated predominately by specific IgE antibodies. Taken together, our results demonstrate that mice infected with flu virus develop virus-specific mast cell degranulation in the skin. Our results may also have implications for the pathogenesis of urticaria or other atopic disorders in humans.