What is the color of the dye added to commercially prepared anti-B blood grouping serum?

• A. Yellow
• B. Blue
• C. Red
• D. Green

Answer: (A)

Color-coding reagents in blood grouping helps technicians quickly identify which antibody is in use and prevents mix-ups in the laboratory. The dye is added as an inert tint during manufacture so the serum is visibly distinct without altering its activity. For commercially prepared anti-B serum, the tint used is yellow, which provides good contrast against the white background and the red blood cells, making agglutination patterns easier to read. Importantly, this dye does not affect the antibody’s ability to bind the B antigen or the results of the test; it’s simply a visual label. Other antisera are color-coded differently to maintain clear differentiation.