Another front in COVID-19's perfect storm

COVID-19 and renal infarct: To be or not to be on anticoagulation

We present a unique case of a male veteran with a history of Castleman disease, presenting with multiple arterial and venous vascular thromboses in the setting of recent Coronavirus (COVID-19)-disease diagnosis. We explore this patient’s morbidity related to thrombotic complications of his COVID-19 diagnosis that were potentially avoidable with a comprehensive outpatient evaluation of his risk for thrombosis, as well as the initiation of anticoagulation and/or antiplatelet therapy given his high risk. Our case highlights the need for a standardized clinical workup of patients in the outpatient setting for risk assessment of vascular thrombosis associated with COVID-19 infection to direct medical management, in order to minimize adverse outcomes, complications requiring inpatient admission, and the need for additional yet limited medical resources and interventions. We propose a minimum of low-dose aspirin 81 mg daily as a reasonable approach for outpatient clinicians to consider, based on their best clinical judgement, when managing mild COVID-19, while other options, such as novel oral anticoagulants, are undergoing further investigation.

SARS-CoV-2 receptor binding domain-specific antibodies activate platelets with features resembling the pathogenic antibodies in heparin-induced thrombocytopenia

Severe COVID-19 is associated with unprecedented thromboembolic complications. We found that hospitalized COVID-19 patients develop immunoglobulin Gs (IgGs) that recognize a complex consisting of platelet factor 4 and heparin similar to those developed in heparin-induced thrombocytopenia and thrombosis (HIT), however, independent of heparin exposure. These antibodies activate platelets in the presence of TLR9 stimuli, stimuli that are prominent in COVID-19. Strikingly, 4 out of 42 antibodies cloned from IgG1+ RBD-binding B cells could activate platelets. These antibodies possessed, in the heavy-chain complementarity-determining region 3, an RKH or Y5 motif that we recently described among platelet-activating antibodies cloned from HIT patients. RKH and Y5 motifs were prevalent among published RBD-specific antibodies, and 3 out of 6 such antibodies tested could activate platelets. Features of platelet activation by these antibodies resemble those by pathogenic HIT antibodies. B cells with an RKH or Y5 motif were robustly expanded in COVID-19 patients. Our study demonstrates that SARS-CoV-2 infection drives the development of a subset of RBD-specific antibodies that can activate platelets and have activation properties and structural features similar to those of the pathogenic HIT antibodies.