Prophylactic immunotherapy in newborn rat endotoxicosis.

The incidence and mortality of gram negative sepsis/septic shock remains high in newborns. In this paper, we postulated that prophylactic immunotherapy may be beneficial in newborn endotoxicosis. Lipopolysaccharide (LPS) tolerant rats were produced by serial Salmonella enteritidis LPS injections, and their sera were used for immunotherapy. Antiserum cotreatment blunted hypoglycemia and lactacidemia in S. enteritidis endotoxicosis and decreased the mortality. In 0-day-old rats, antiserum cotreatment groups had a decreased mortality when injected with S. enteritidis LPS (P less than .001), S. typhosa LPS (P less than .005), and Escherichia coli LPS (P less than .05). This global protection suggested that antibody to S. enteritidis LPS could be due to a common LPS antigen. Prophylactic antiserum administration to pregnant rats on the 18th day of gestation decreased the mortality of S. enteritidis endotoxicosis in 0-day-old rats (P less than .001). The prophylactic effects of antiserum was achieved by transplacental passage to the conceptus. We conclude that prophylactic as well simultaneous immunotherapy was beneficial in newborn rat endotoxicosis.