Assessment of host resistance in critically ill surgical patients by the response to recall skin antigens

The cell-mediated immunity (CMI) of 47 critically ill surgical patients admitted to an Intensive Therapy Unit was assessed by their response to recall skin antigens and found to be markedly reduced. Thirty-seven patients showed no reaction to initial skin testing (NR), and there were 21 deaths in this group. Ten patients reacted (R) to initial skin testing and only one of these patients died (p<0.025). Repeat skin testing was performed on 22 NR patients. Eight became R on repeat testing and there was one death in this group, whilst 14 remained NR and there were 11 deaths in this group (p<0.025). The major clinical difference between R and NR patients was a greater incidence of severe sepsis in the NR patients. These findings suggest that the use of recall skin antigens to assess CMI may be a valuable investigation in critically ill surgical patients and that initial and persisting failure to react to skin tests is associated with a poor outcome.