Kotler had planned to use acetaminophen, which is most often sold under the brand-name Tylenol, as a contrast to aspirin in studying whether aspirin stimulates production of vital disease-fighting chemicals, interleukins and interferons, in AIDS patients. Now, he says he'll use a placebo instead.

The committee recommended that the FDA issue new labels on all Tylenol-containing products warning against the risk of mixing high levels of alcohol intake with ingestion of acetaminophen. But the FDA, which was also researching ulcerative bleeding associated with ibuprofen and aspirin in a separate study, decided to hold up warnings on acetaminophen until it could make a definite statement on all three analgesics.

Kotler, hypothesizing that aspirin could play a similar role in promoting immmune response to HIV, planned to test the hypothesis in a clinical study of 96 people, half of whom would receive a control - which was to be acetaminophen. But when Kotler learned of [Leonore Herzenberg]'s work he changed plans, dropping acetaminophen from the study.