Host resistance to infection was measured by the in vivo response to 5 delayed hypersensitivity antigens and to sensitivity and challenge by dinitrochlorobenzene (DNCB) in 55 seriously ill or injured patients and in 50 preoperative patients. A close correlation between infections, septicemia, death related to infection and anergy was found in the postoperative and post injury patients and was predictive of these complications in the patients studied preoperatively. Decreased body cell mass was noted in both the anergic and non-anergic patients which was consistent with protein-calorie malnutrition but the two groups were not significantly different. A serum factor which inhibited cellular immunity in vitro was found in 4 patients. This factor disappeared in the two patients who recovered. The study suggests the therapeutic value of the in vivo measurement of delayed hypersensitivity in seriously ill and especially preoperative patients in whom specific or non-specific stimulation of cell mediated immunity might alter the risk of infection.

Over the last 5 years, because of a reduction in overall patient mortality, the contribution of a reduced DTH response to septic related mortality has lost statistical significance in elective surgical patients. A reduced DTH response maintains its strong association to sepsis-related mortality in intensive care/trauma patients, and this is the group on which future research efforts should be concentrated.

Mice were injected from day of birth onward with rabbit anti-mouse IgM antiserum or purified rabbit anti-mouse IgM antibodies. These mice completely lacked Ig-positive cells or serum Ig, as analyzed by specific fluoresceinated antibodies on the fluorescence-activated cell sorter (FACS-II), by polyclonal B cell mitogens and by specific precipitation in agar. These animals were then primed in vivo by antigen emulsified in complete Freund's adjuvant, and, subsequently, their draining lymph nodes were tested for their T cell proliferative responses in vitro, to the relevant antigen and were found to be severely impaired. However, the antigen-presenting capacity of both spleen cells and thioglycollate-induced peritoneal cells was found to be intact.