IN AN EARLIER comment on the landmark article by Ziegler and coworkers1 on the treatment of gram-negative bacteremia and septic shock with HA-1A human monoclonal antibodies, our group2 expressed discomfort with their recommendation that these antibodies to endotoxin be administered routinely. It was then apparent that successful treatment with this anti—lipid A antibody was contingent on the clinician's capability to make an early diagnosis of bacteremia and to further establish that the bacteremia was caused by endotoxin-producing enteric bacilli. Otherwise, the majority of patients would be exposed to potential risks without likelihood of benefit and with alarmingly high monetary costs. Subsequent articles reaffirmed these conclusions and the Food and Drug Administration disapproved HA-1A antibody for routine clinical use in the United States. Unfortunately, trials of the murine anti—endotoxin antibody, E5, were also disappointing, as were the trials on inhibitors of nonspecific mediators with antibodies to tumor necrosis factor