Background: Immunoglobulin E (IgE)-mediated allergies are increasing in prevalence, with IgE-mediated food allergies currently affecting up to 10% of children and 6% of adults worldwide. The mechanisms underpinning the first phase of IgE-mediated allergy, allergic sensitization, are still not clear. Recently, the potential involvement of lipids in allergic sensitization has been proposed, with reports that they can bind allergenic proteins and act on immune cells to skew to a T helper type 2 (Th2) response.Objectives: The objective of this systematic review is to determine if there is strong evidence for the role of lipids in allergic sensitization.Methods: Nineteen studies were reviewed, ten of which were relevant to lipids in allergic sensitization to food allergens, nine relevant to lipids in aeroallergen sensitization.Results: The results provide strong evidence for the role of lipids in allergies. Intrinsic lipids from allergen sources can interact with allergenic proteins to predominantly enhance but also inhibit allergic sensitization through various mechanisms. Proposed mechanisms included reducing the gastrointestinal degradation of allergenic proteins by altering protein structure, reducing dendritic cell (DC) uptake of allergenic proteins to reduce immune tolerance, regulating Th2 cytokines, activating invariant natural killer T (iNKT) cells through CD1d presentation, and directly acting upon toll-like receptors (TLRs), epithelial cells, keratinocytes, and DCs.Conclusion: The current literature suggests intrinsic lipids are key influencers of allergic sensitization. Further research utilising human relevant in vitro models and clinical studies are needed to give a reliable account of the role of lipids in allergic sensitization.

Objectives COVID-19 vaccine responses in rare autoimmune rheumatic diseases (RAIRD) remain poorly understood, in particular there is little known about whether people develop effective T cell responses. We conducted an observational study to evaluate the short-term humoral and cell-mediated T cell response after the second SARS-CoV-2 vaccination in RAIRD patients compared with healthy controls (HC). Methods Blood samples were collected after the second dose and anti-spike, anti-nucleocapsid antibody levels and SARS-CoV-2 specific T cell responses were measured and compared with HC. Activation induced marker and deep phenotyping assays were used to identify differences in T cells between high and low/no antibody groups, followed by multi-dimensional clustering. Results 50 patients with RAIRD were included (31 with AAV, 4 with other systemic vasculitis, 9 with SLE and 6 with myositis). Median anti-spike levels were significantly lower in RAIRD compared with HC (p< 0.0001). 15 (33%) patients had undetectable and 26 (57%) had lower levels than the lowest HC. Rituximab in the last 12 months (p= 0.003) was associated with reduced immunogenicity compared with a longer pre-vaccination period. There was a significant difference in B cell percentages (p= 0.03) and spike-specific CD4+ T cells (p= 0.02) between no/low antibody vs. high antibody groups. Patients in the no/low antibody group had a higher percentage of terminally differentiated (exhausted) T cells. Conclusions Following two doses, most RAIRD patients have lower antibody levels than the lowest HC and lower anti-spike T cells. RAIRD patients with low/no antibodies have diminished numbers and poor quality of memory T cells which lack proliferative and functional capacities.