Effect of late administration of anti-TNα antibodies on a Salmonellainfection in the mouse model

The effect of late administration of anti-TNFα antibodies on the course of a Salmonellainfection in mice was evaluated. Administration of anti-TNFα antiserum as late as day 5 after challenge enhanced a sublethal primary infection with the virulent Salmonella typhimuriumC5 in innately resistant (Itys) A/J mice by preventing the suppression of exponential bacterial growth in the reticuloendothelial system (RES) (plateau phase). When the anti-TNFα treatment was started well after the establishment of the plateau (day 7) a prompt relapse of the infection occurred, with the rapid resurgence of bacterial growth in the reticuloendothelial system leading to the death of the animals. In contrast, late administration of the antiserum did not affect the clearance from the tissues of an avirulent temperature-sensitive mutant of S. typhimuriumC5 (C5TS).