C3a Complement Peptide Receptor Antibodies

C3a is a small 77–amino acid peptide generated during activation of the complement system through cleavage of complement component C3. It functions as an anaphylatoxin and plays a key role in innate immunity and inflammatory amplification. C3a exerts its biological effects by binding to the C3a receptor (C3aR) on immune and certain non-immune cells, triggering intracellular signaling cascades. Downstream signaling typically involves Gi and Gq protein pathways, leading to modulation of cAMP levels, intracellular calcium mobilization, and activation of MAPK-dependent responses. C3a is widely involved in chemotaxis, mast cell degranulation, cytokine release, and increased vascular permeability, contributing to host defense but also to pathological inflammation. Dysregulated C3a signaling has been implicated in conditions such as asthma, sepsis, autoimmune diseases, and neuroinflammatory disorders. There are currently no approved drugs that directly neutralize C3a, although complement-targeting therapies in general are an active area of clinical development. Ongoing research aims to better define the therapeutic potential of modulating the C3a–C3aR axis in inflammatory and immune-mediated diseases. For more information on C3a receptor pharmacology please refer to the IUPHAR database. For further reading refer to:

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Nürge B, Schulz AL, Kaemmerer D, Sänger J, Evert K, Schulz S, Lupp A. Immunohistochemical identification of complement peptide C5a receptor 1 (C5aR1) in non-neoplastic and neoplastic human tissues. PLoS One. 2021 Feb 19;16(2):e0246939. doi: 10.1371/journal.pone.0246939. PMID: 33606748; PMCID: PMC7894821.