Some believe that the body may initiate an autoimmune response when SARS-CoV-2 is attached to an ACE2 receptor. The body may consider this complex antigenic, meaning it produces antibodies. However, these antibodies would target both the virus and ACE2. This theory is substantiated by:

• the patterns of lung damage in patients with Pulmonary Hypertension secondary to Scleroderma, which is hallmarked by high levels of anti-ACE2 antibodies
• the severity of COVID-19 immune responses in those with cardiovascular disease and hypertension, who would be likely to have increased levels of ACE2 receptors in their blood serum

Measuring ACE2 levels in serum could be a way of predicting at-risk groups for ARDS (acute respiratory distress syndrome) and other hyperimmune responses.