Phenotyping of Angiotensin-I-converting Enzyme in Patients with Systemic Manifestations of Sarcoidosis
The variety of clinical manifestations of sarcoidosis indicates the systemic nature of the disease, which significantly complicates the diagnosis. Using the method of determining changes in tertiary structure of angiotensin-I-converting enzyme (ACE), organo- and tissue-specific conformation of the enzyme was demonstrated. ACE phenotyping was performed using citrated plasma from 85 patients with sarcoidosis. The method included the simultaneous determination of ACE activity on 2 substrates, calculation of the ratio of ACE activities for hydrolysis on these substrates, determination of the levels of immunoreactive ACE protein and ACE conformation using a set of monoclonal antibodies to enzyme with subsequent statistical processing of the data. Differences were found in patients with sarcoidosis with high disease activity in phenotyping parameters 1G12 and 1G12/9B9 (p < 0.05), as well as change in i1A8 and i1A8/9B9 indices in spleen sarcoidosis (p < 0.05). A significant effect on phenotyping parameters was revealed not only of ACE inhibitors, but also of systemic glucocorticosteroids. Phenotyping seems to be a promising screening method for diagnosis of active course of sarcoidosis. However, the possibilities of the method in assessing the prevalence of the disease, including organ specificity, are insufficiently reasoned.