B. TEST FOR SECRETOR STATUS

1. Dilute saliva with an equal volume of saline (undiluted saliva contains nonspecific glycoproteins that can inhibit antisera and lead to incorrect results). 2. Add one drop of diluted antiserum to an appropriately labeled tube (anti-A, anti-B, anti H). For dilution, titrate anti-H, anti-A, and anti-B, testing against appropriate cells at immediate spin. Select the dilution giving 2+ agglutination, and prepare a sufficient quantity to complete the test. 3. Add one drop of supernatant saliva to each tube. Mix and incubate at room temperature for 8 to 10 minutes. 4. Add one drop of the appropriate indicator cells (A, B, or O cells) to the properly labeled tube. 5. Mix and incubate at room temperature for 30 to 60 minutes. 6. Centrifuge for 15 to 30 sec at 3600 rpm 7. Observe for macroscopic agglutination.