What lectin should be used first to resolve the discrepancy in the given serum results?

Using Dolichos biflorus lectin is appropriate because it specifically agglutinates group A cells due to its strong reactivity with the A antigen. In blood banking, discrepancies often arise from unexpected or weak reactions in serological testing, especially when determining blood group types. Applying Dolichos biflorus as the first lectin helps clarify whether the presence of A antigen is correctly identified.

When discrepancies involve weak A or Ax phenotypes, Dolichos biflorus can effectively distinguish these by showing strong agglutination with typical A antigens while remaining non-reactive with group O or B cells, which aids in resolving such classification issues. This specificity makes it valuable in the initial steps of troubleshooting serological discrepancies.

Other lectins also have their roles in addressing different antigens or specific scenarios but are less effective for resolving the specific types of discrepancies where A antigen presence is in question. Thus, starting with Dolichos biflorus is a strategic choice in blood banking practices.