Anaphylaxis caused by allergen sensitization and vaccination is a serious health concern. The severity of anaphylaxis is associated with the presence of immunoglobulin E (IgE) antibodies that bind to allergens with a high affinity. Here, we report the development of a unique Interleukin-13 (IL-13)-producing follicular helper T (T_FH) cell subset, designated T_FH2 cells, which is tightly associated with the production of high-affinity IgE antibodies. T_FH2 cells had a transcriptionally hybrid phenotype between T_H2 and T_FH cells, which express GATA-binding protein 3 (Gata3) and B-cell/CLL lymphoma 6 (BCL-6), respectively. Adaptive transfer experiments demonstrated that type 2 helper T (T_H2) cells were capable of differentiating into T_FH2 cells upon secondary antigen stimulation. The type 2 T_FH (T_FH2) conversion process was entirely attenuated in T cell-specific deficient mice of Bcl6 (Bcl6^f/f cd4-cre; Bcl6^ΔT). Moreover, the transfer of IL-13 defective T_H2 cells partially inhibited IgE responses and significantly decreased the high-affinity IgE, even though T_FH development was intact. Therefore, IL-13 from T_FH2 cells controlled the selective enrichment of IgE⁺ B-cells with a high affinity for allergens. A previously undefined unique T_FH subset, T_FH2, likely contributes to IgE responses. This suggests that the accumulation of antigen-specific T_H2 cells in human patients with allergies is a high-risk factor for IgE-dependent allergic diseases.

Human monkeypox (hMPX) is a smallpox-like disease caused by the monkeypox virus (MPXV) that belongs to the genus of Orthopoxvirus, in the family of Poxviridae. The natural hosts of MPXV are species of rodents, which are found in habitats in Central and Western Africa. Sporadic cases of patients with hMPX have been identified in central Africa since the discovery of the first cases in the early 1970s in the Democratic Republic of the Congo (DRC) and Western African countries. Since May 2022 (and up to the end of October 2022), more than 75,000 patients with hMPX have been reported, mainly in European and American countries. In the current outbreak, MPXV is transmitted from human to human, through close sexual contact, especially among men who have sex with men (MSM). Safe and effective third-generation smallpox vaccines, namely, LC16m8 and modified vaccinia virus Ankara (MVA), are effective in protecting vaccinees from hMPX. It is highly possible that immediate vaccination of close contacts with MVA or LC16m8, before disease onset, may be effective in reducing the severity of hMPX if infected. A proper vaccination program would reduce the scale of the current hMPX outbreak. Furthermore, hMPX in endemic areas should be prevented through mass vaccination programs with third-generation vaccines for those living in these regions. Notably, the current hMPX outbreak is mainly associated with community-specific MSM circumstances. Special consideration should be given to patients with hMPX, who must be protected from societal discrimination.

Pulse oximetry is a noninvasive technique for the continuous monitoring of arterial oxygen saturation using an oximeter, a standard medical device used for assessing respiratory function. The development of pulse oximeters for the production of generic medical devices is expected to continue. Clinical trials to evaluate oxygen saturation measurements are necessary for the manufacture and commercialization of pulse oximeters. However, no standardized guidelines or methodologies exist for conducting such clinical trials. Therefore, we exploratively aimed to create a hypoxic state in humans to conduct a clinical trial for generic pulse oximeters using a gas-mixing device.