Development of a Complement Hemolysis Assay Using Aldehyde-Modified Human Erythrocytes
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Background
Complement-mediated hemolysis assays are essential for assessing immune function and diagnosing complement-related disorders. Conventional human erythrocyte derivatization with 2,4,6-trinitrobenzene sulfonic acid (TNBS) can induce nonspecific hemolysis and optical interference, complicating interpretation. Identifying a more biocompatible electrophile could improve assay specificity and reliability.
Methods
A panel of aldehydes was screened for electrophilicity using a nucleophile consumption assay with glycine as a model nucleophile. Glyoxylic acid was selected based on reactivity, solubility, and visual neutrality, then neutralized with sodium bicarbonate to minimize baseline hemolysis. Human erythrocytes were sequentially treated with pancreatin and glyoxylic acid to generate glyoxylic acid–pancreatin–treated erythrocytes (GxPEs). Complement-mediated hemolysis was assessed using normal human serum, heat-inactivated serum, and pathway-specific conditions, with CH50 values calculated for total, alternative, and non-alternative pathways.
Results
GxPEs exhibited robust complement-specific hemolysis (maximum 93.56%) with negligible background activity in heat-inactivated serum. CH50 analysis confirmed activation via both alternative (0.9514 μL) and non-alternative (1.963 μL) pathways. Reconstitution experiments with factor B–depleted cryoprecipitate and cryosupernatant fractions demonstrated dependence on small complement components such as C2 and C4.
Conclusions
Glyoxylic acid derivatization yields a reproducible, optically quiet, and complement-specific erythrocyte substrate suitable for functional hemolysis assays. This method offers a practical platform for complement diagnostics, research applications, and therapeutic evaluation.
