Materials & methods
Three patients with diagnosis of COVID-19 classified as critically ill (two) and severely ill (one) were included in an expanded access trial to receive itolizumab in addition to standard treatment (http://rpcec.sld.cu/trials/RPCEC00000311-En). The study was approved by a central ethical review board, created especially for COVID-19 and by the Cuban Regulatory Agency (CECMED). Before the treatment, informed consent was obtained from enrolled patient.
Laboratory results included blood routine, leucocyte subsets and blood biochemical parameters were collected. The level of inflammatory cytokines was measured using human validated commercially available kit from R&D Systems (MN, USA): human IL-6 Quantikine ELISA Kit (Cat# S6050), human IL-1 beta/IL-1F2 Quantikine ELISA Kit (Cat# SLB50) and human TNF-α Quantikine ELISA Kit (Cat# STA00D). In the case of IL-6, the normal range of this cytokine in sera is between 0 and 7 pg/ml [17]. We used intra-assay precision and inter-assay precision methods to evaluate precision in this study.
For intra-assay precision (precision within an assay), three samples of known concentration were tested on one plate to assess intra-assay precision.
For inter-assay precision (precision between assays), three samples of known concentration were tested in separate assays to assess inter-assay precision.