In the primary immune response, detectable antibody appears only after
- A. a few minutes
- B. about an hour
- C. several days
- D. about a year
Explanation
The lag of roughly five to ten days is the time needed for the one matching lymphocyte to be selected, to divide into a clone and for plasma cells to build up antibody production. This delay is why a first infection makes a person ill while the same infection later may pass unnoticed. In the secondary response the lag shrinks to a day or two and the antibody level reaches a far higher peak.