Advances in the human immunoglobulin G purification from blood and colostrum <i>via</i> mild chromatographic strategies

Abstract BACKGROUND Research on breastmilk passive immunity requires enriching antibodies from complex samples for downstream assays. Currently, most chromatographic IgG purification processes meet the required purity level but could compromise the tridimensional structure of IgG and, therefore, their functionality. This work aims to establish mild chromatography strategies, using the Melon™ Gel Purification Kit, to purify IgG from human plasma and colostrum. The effect of multiple experimental parameters, such as purification steps, initial protein concentration, and sample volume, was tested. Size exclusion chromatography (SEC) was used as a complementary step. The in vitro functionality of the enriched IgG from both tissues was tested by a phagocytosis assay with peripheral blood neutrophils and E. coli bioparticles. RESULTS In human plasma, the initial protein concentration was inversely proportional to the IgG purity, being linear in the range between 1.5 and 4.5 mg mL −1 , where the IgG purity ranged between 55 and 97%. The adjustment of plasma samples at 1.5 mg mL −1 of total protein increased the IgG purity up to 98% in a single purification step. On the other hand, when the protein concentration of colostrum samples was adjusted, IgG purity reached only 9.3%. The maximum IgG purity of colostrum samples was 25% after two purification steps. The remaining contaminant proteins can be eliminated by SEC. Finally, IgG samples showed significant enhanced phagocytosis by peripheral blood neutrophils. CONCLUSIONS The present work provides chromatographic purification strategies for purifying and enriching IgG (avoiding structural modifications) from complex and volume‐limited samples. © 2025 Society of Chemical Industry (SCI).