Inflammation and blood clotting seen in very severe cases of Covid-19 may be caused by the antibodies sent to fight the infectious disease activating unnecessary platelet activity in the lungs, according to researchers.Platelets are small cells found in blood which form clots to stop or prevent bleeding, but when they don't function properly, it can lead to serious health concerns such as strokes and heart attacks.The study, published in the journal Blood, took antibodies produced to fight the coronavirus's spike protein, from people with severe Covid-19 infections, and cloned them in a lab to study them.The team, led by researchers from the Imperial College London, found that the small sugars found on the surface of these antibodies were different to antibodies from healthy individuals, and when those cloned antibodies were introduced in a lab to blood cells taken from healthy donors, there was an observed increase in platelet activity.The team also found that it was possible to reduce or stop platelets from responding in this way in the laboratory by treating blood with active ingredients from different medications which is known to either inhibit platelet function or immune responses.The findings suggest that it may be possible for drugs that are currently used to treat immune system problems to reduce or stop the cells from producing an exaggerated platelet response.