Table Sugar as an Accessible Substitute for Purified Sucrose in the Preparation of C3b/C4b-Coated Red Blood Cells

Abstract

Quality control (QC) of anti-complement serological assays is a core prerequisite for reliable pre-transfusion testing and direct antiglobulin test (DAT) interpretation in clinical immunohematology laboratories. C3b/C4b-coated red blood cells (RBCs) serve as critical control reagents for validating negative results of anti-C3 reagent tests, ruling out false-negative reactions caused by inactive antisera or inadequate washing procedures in routine immunohematological workflows. Two standardized protocols (Method 7-A and 7-B) have been established for the preparation of C3b/C4b-coated RBCs, differing exclusively in sucrose source while retaining identical reaction principles and operational procedures. However, the key difference—the substitution of 10% sucrose in 7‑A with 10% “sugar water” prepared from granulated white table sugar in 7‑B—deserves closer examination and commentary. Herein, we summarize the technical characteristics, fundamental mechanisms, and practical clinical value of the two methods, highlighting the feasibility and advantages of table sugar as a substitute for purified commercial sucrose.