Chemokine CXCL4 key to rare COVID-19 vaccine side effect

Posted by Brian Volkman on 11/29/2021 to Literature Highlights

A study published this summer in Nature explains how platelet-activating antibodies cause a rare adverse effect known as vaccine-induced immune thrombotic thrombocytopenia (VITT). VITT has been associated with COVID-19 vaccines that employ adenoviral vectors for immunogen DNA delivery (as opposed to mRNA vaccines from Pfizer/BioNTech and Moderna, e.g.). VITT is similar to heparin-induced thrombocytopenia (HIT) in that they both result from antibodies against the chemokine CXCL4 (also known as platelet factor 4 or PF4). CXCL4 binds heparin with high affinity, and HIT is a rare side effect of the use of heparin to prevent blood clots. The authors found that the antibodies from VITT patients mimicked the CXCL4-heparin interaction, promoting the clustering of CXCL4-antibody complexes and platelet activation that can lead to thrombosis. Protein Foundry manufactures the recombinant human and mouse CXCL4 that is used by leading HIT researchers and diagnostic laboratories. Both proteins are in stock, biotin and fluorescent dye labeled versions are available, and custom CXCL4 variants can be delivered in 6 weeks or less.