Bee venom processes human skin lipids for presentation by CD1a.
Bottom Line: Patient studies showed that injected PLA2 generates lysophospholipids within human skin in vivo, and polyclonal T cell responses are dependent on CD1a protein and PLA2.These findings support a previously unknown skin immune response based on T cell recognition of CD1a proteins and lipid neoantigen generated in vivo by phospholipases.The findings have implications for skin barrier sensing by T cells and mechanisms underlying phospholipase-dependent inflammatory skin disease.
Affiliation: Division of Rheumatology, Immunology and Allergy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, 02114.Show MeSH
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Mentions: Stinging insects in the genera vespula (wasp) and apis (bee) generate a local intradermal inflammatory response. To investigate a possible role of CD1, we obtained CD3+ T cells from healthy adult individuals and mixed them with wasp venom-treated and irradiated K562-CD1 APCs, which were mock transfected or transfected with either CD1a, CD1b, CD1c, or CD1d. As expected based on prior work (de Jong et al., 2014), we observed low but detectable alloreactive background responses of ∼1 in 2,000 T cells after 12–14 d in culture to mock-transfected target cells in donor C1175 (Fig. 1 A, left), which is representative of three donors. In the absence of venom, T cells showed responses to K562-CD1a cells at rates higher than to mock transfected cells or cells expressing other CD1 isoforms, confirming the presence and relatively high rates of CD1a autoreactive T cells seen previously (de Jong et al., 2010, 2014; de Lalla et al., 2011). Further, polyclonal responses to wasp venom above background levels were detected, but were seen only when using CD1a-expressing cells as targets (P < 0.05, Fig. 1 A, left, representative of three donors). These responses demonstrate that a T cell response to wasp venom is restricted by CD1a proteins.
Affiliation: Division of Rheumatology, Immunology and Allergy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, 02114.