Vaccines and allergic reactions: The past, the current COVID-19 pandemic, and future perspectives.

Vaccines are essential public health tools with a favorable safety profile and prophylactic effectiveness that have historically played significant roles in reducing infectious disease burden in populations, when the majority of individuals are vaccinated. The COVID-19 vaccines are expected to have similar positive impacts on health across the globe. While serious allergic reactions to vaccines are rare, their underlying mechanisms and implications for clinical management should be considered to provide individuals with the safest care possible. In this review, we provide an overview of different types of allergic adverse reactions that can potentially occur after vaccination and individual vaccine components capable of causing the allergic adverse reactions. We present the incidence of allergic adverse reactions during clinical studies and through post-authorization and post-marketing surveillance and provide plausible causes of these reactions based on potential allergenic components present in several common vaccines. Additionally, we review implications for individual diagnosis and management and vaccine manufacturing overall. Finally, we suggest areas for future research.

Why we scratch: Function and dysfunction.

Itch is a common sensation that drives an intense urge to scratch. Itch and scratching have persisted in humans and many other species, suggesting that they play an important role in survival. This commentary discusses the function of itch as a danger signal, why itch feels unpleasant and why we feel relief and pleasure when we scratch an itch. In addition, we explore the ways that this system becomes dysfunctional in conditions of chronic itch and important implications for treatment.

Providing a Safe Nest for Improved Health Care Outcomes in Pregnant Women With Asthma.

There is a large unmet disease burden arising from asthma in pregnancy. Pregnant women affected by moderate to severe asthma have an increased risk for adverse perinatal outcomes. This can be worsened by social determinants of health, which are social and environmental conditions that affect health and the quality of life. Here we present the case of a medically complex pregnant woman with worsening asthma and challenges in optimizing positive outcomes for both the mother and baby during the perinatal period. This case captures several elements of social determinants of health that affect health outcomes most notably in non-White patients, including chronic exposure to air pollution contributing to asthma severity and reduced access to health care specialists.

Gender specificity of altered human immune cytokine profiles in aging.

Cytokine generation by T cells and monocytes was determined for 50 subjects aged 65 yr or older and concurrently studied young subjects individually matched to each old subject for sex, race, and national origin. Highly significant differences between cytokine levels of old and young subjects all were gender specific. For T cells stimulated with anti-CD3 plus anti-CD28 antibodies, mean ratios of IFN-gamma generation for healthy old to young subjects were 0.22 for men (P<0.001; n=15) and 3.35 for women (P<0.001; n=13), and those of IL-17 were 0.30 for men (P<0.001) and no difference for women. CD8 T cells were the source of high IFN-gamma in healthy old women. For old men with an inflammatory or immune disease (n=10), mean old to young ratios of T-cell-generated IFN-gamma and IL-17 increased with disease severity up to 5.78 and 2.97 (both P<0.01), respectively, without changes for old women with similar diseases (n=12). For differentiated LPS-stimulated monocytes, old to young ratios of TNF-alpha and IL-6 generation were high only in women with immune or inflammatory disease (2.38, P<0.05 and 1.62, P<0.01, respectively), whereas ratios of IFN-gamma-evoked IP-10 chemokine were low in all groups. Alterations in immune cytokine profiles with aging show significant gender specificity.

Immunosuppressive human anti-lymphocyte autoantibodies specific for the type 1 sphingosine 1-phosphate receptor.

Anti-lymphocyte antibodies (Abs) that suppress T-cell chemotactic and other responses to sphingosine 1-phosphate (S1P), but not to chemokines, were found in a lymphopenic patient with recurrent infections. Lymphocyte type 1 S1P receptor (S1P(1)) that transduces S1P chemotactic stimulation was recognized by patient Abs in Western blots of T cells, S1P(1) transfectants, and S1P(1)-hemagglutinin purified by monoclonal anti-hemagglutinin Ab absorption. The amino terminus of S1P(1), but not any extracellular loop, prevented anti-S1P(1) Ab suppression of S1P(1) signaling and T-cell chemotaxis to S1P. Human purified anti-S1P(1) Abs decreased mouse blood lymphocyte levels by a mean of 72%, suppressed mouse T-cell chemotaxis to S1P in vivo, and significantly reduced the severity of dextran sodium sulfate-induced colitis in mice. Human Abs to the amino terminus of S1P(1) suppress T-cell trafficking sufficiently to impair host defense and provide therapeutic immunosuppression.

Noxious heat and scratching decrease histamine-induced itch and skin blood flow.

The aim of this study was to assess the effect of thermal stimuli or distal scratching on skin blood flow and histamine-induced itch in healthy volunteers. Twenty-one healthy volunteers participated in the study. Baseline measurements of skin blood flow were obtained on the flexor aspect of the forearm. These measurements were compared with skin blood flow after various stimuli: heating the skin, cooling the skin, noxious cold 2 degrees C, noxious heat 49 degrees C, and scratching via a brush with controlled pressure. Afterwards histamine iontophoresis was performed and skin blood flow and itch intensity were measured immediately after the above-mentioned stimuli. Scratching reduced mean histamine-induced skin blood flow and itch intensity. Noxious heat pain increased basal skin blood flow but reduced histamine-induced maximal skin blood flow and itch intensity. Cold pain and cooling reduced itch intensity, but neither affected histamine-induced skin blood flow. Sub-noxious warming the skin did not affect the skin blood flow or itch intensity. These findings suggest that heat pain and scratching may inhibit itch through a neurogenic mechanism that also affects skin blood flow.