The delayed hypersensitivity response and host resistance in surgical patients. 20 years later.

OBJECTIVE: A 20-year follow-up was conducted on research into the implications of a lack of a delayed-type hypersensitivity (DTH) skin test response among surgical patients. SUMMARY BACKGROUND DATA: The authors' original report showed that a failed DTH response was associated with increased hospital mortality, but the role of specific and nonspecific host defense elements, comorbid factors, nutritional supplementation, and the mechanism for anergy in this adverse outcome was unknown. METHODS: A data base of 4292 patients was analyzed and reported on individual studies designed to answer some of the above questions. RESULTS: Prospective studies showed a strong association between the DTH response and mortality: reactive patients, 2.9% (75/2576); anergic patients, 20.9% (239/1142, chi square = 265, p < 0.0000001). Antibody response to protein antigens was reduced in anergic patients. Antibody response to polysaccharide antigens was normal in all patients. The hallmark of anergy is a lack of T cells in the skin, as measured by mRNA signal (CD3) for T cells. The nonspecific component of host defense, as measured by circulating and exudate polymorphonuclear cell function, showed no statistically significant difference between elective reactive and elective anergic patients. Notwithstanding some mild malnutrition in anergic patients, parental nutrition failed to correct the DTH response or many of the cellular immune functions measured. CONCLUSIONS: 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.     

Clinical outcome of seriously ill surgical patients with intra-abdominal infection depends on both physiologic (APACHE II score) and immunologic (DTH score) alterations.

The delayed-type hypersensitivity (DTH) response and the APACHE II score in 118 patients with surgical infections were measured prospectively and related to outcome. Logistic regression analysis generated the equation: [formula: see text]. The risk assessment as calculated by this model was compared to that using the APACHE II system alone in a separate group of 354 patients. There was an improvement in the predictive capacity of the APACHE II + DTH equation compared to APACHE II alone, as shown by a better fit of expected and observed deaths, an improved Goodman-Kruskal G statistic, and a larger area under the receiver operating characteristic curve. It is concluded that the DTH response (a broad marker of immunocompetence) is an independent prognostic factor in surgical patients and can be used in combination with the APACHE II score (a measure of acute physiology) to estimate better the outcome of surgical patients.     

Treatment of 34 patients with myelodysplastic syndromes with 13-CIS retinoic acid

Abstract: Thirty-four patients with myelodysplastic syndromes, 23 men and 11 women, aged between 47 and 80 years, with all types of myelodysplastic syndromes were treated with 13-cis-retinoic acid. The dose of retinoic acid ranged between 10 and 60 mg/m²/daily and was administered in combination with vitamin E to diminish side effects. The duration of treatment was 3 months to 5 years. Partial remission was achieved in 4 patients, 1 with RA type, 2 with RAEB and 1 with CMML. Survival ranged from 1 to 5 years. Patients who received retinoic acid developed mild side effects. In conclusion, the administration of 13-cis-retinoic acid improves the hematological picture in a small number of MDS patients (11.7%).     

Therapeutic approaches to anergy in surgical patients. Surgery and levamisole.

Skin tests (ST) in 1332 patients are associated with increased morbidity from sepsis. Patients with normal skin tests had a 7% major sepsis rate and 2% mortality rate. Thirty-six per cent of anergic (A) patients and 21% of relatively anergic (RA) patients died; 52% of A patients and 34% of RA patients had sepsis. These data include all patients studied and represent their worst skin test. Two studies were done. The first was a retrospective evaluation of effect of surgery upon 49 anergic patients with biliary tract disease, colon cancer, bowel obstruction, hypovolemia and visceral abscesses. The patients did not receive total parenteral nutrition (TPN). The data show that surgery without TPN can reverse the anergic state and did so in 84% of patients reported. The second study was a prospective, double-blind, randomized trial of the effect of levamisole on skin tests, neutrophil chemotaxis (CTX), sepsis and mortality iin 39 preoperative anergic patients. Major sepsis was significantly increased in placebo group (p less than 0.05). Mortality, minor sepsis, restoration of skin tests and chemotaxis were somewhat better in levamisole patients but not statistically so. These studies show that in addition to TPN, surgery and immunorestorative drugs are viable approaches to the management of selected anergic patients.     

Clinical assessment of host defense

Host defense mechanisms are a determinant of infection. Anergy in surgical patients is a signal of broadly based immune deficits, which include abnormalities in specific and local nonspecific antibacterial defenses and related life-threatening sepsis. Analysis of these abnormalities and other risk factors allows us to generate a long-predictive equation of individual probability of death.     

The role of secondary metabolism in the metabolic activation of 7,12-dimethylbenz[a]anthracene by rat liver microsomes

The effect of induction by either phenobarbital (PB) or 3-methylcholanthrene(MC) on the kinetics of both primary and secondary metabolismof 7,12-dimethylbenz[a]-anthracene (DMBA) have been studied.PB and MC induction stimulate the initial rate of total DMBAmetabolism 4- and 8-fold, respectively. Individual metabolitesexhibited distinct time courses dependent on the inducer. Withboth induced and uninduced microsomes, formation of DMBA 5,6-dihydrodiolexhibited a 2–5 min time lag before reaching a maximumrate while, in contrast, formation of 7-hydroxy-methyl-12-methylbenz[a]anthracene(7HOMMBA) declined substantially from linearity at a very earlypoint in the reaction. This was most apparent after 2 min andtotal levels decreased after 5 min. Regioselectivity for bothDMBA and 7HOMMBA were measured based on the initial rates ofmono-oxygenation derived from these kinetics. In each set ofmicrosomes, prior 7-hydroxylation redirected metabolism towardsDMBA 3,4-dihydrodiol formation and away from 5,6-dihydrodiol.Large differences were noted for the effectiveness and regioselectivityof secondary metabolism via 7HOMMBA. MC-induced liver microsomesexhibited a stronger preference for secondary metabolism of7HOMMBA than PB-induced and control microsomes. In all cases,7HOMMBA dihydrodiols, formed from DMBA, appeared in the sameratio as when formed directly from 7HOMMBA, suggesting formationfrom 7HOMMBA rather than from 7-hydroxylation of primary dihydrodiols.The extent of secondary metabolism of primary products was calculatedas the difference between the calculated formation (determinedfrom the appropriate regioselectivity and DMBA disappearance)and the quantitated level at a particular reaction time. However,for MC-induced microsomes, quantitation of 7HOMMBA mono-oxygenatedmetabolites accounted for <50% of the calculated 7HOMMBAsecondary metabolism. This discrepancy results from selectivefurther oxidation of 7HOMMBA phenols. For control and PB-inducedliver microsomes, quantitation of identifiable 7HOMMBA mono-oxygenatedmetabolites agreed well with calculated secondary 7HOMMBA metabolism.Based on the results presented here, factors that favor hydroxylationof PAH prior to bay-region diol-epoxide formation are discussed.     

Immunological responses to chronic heat exposure and food restriction in rats

Immunological variables were studied in rats chronically exposed to high environmental temperature (35 degrees C). Responses were compared with those of rats at 25 degrees C both fed ad libitum and pair fed to the decreased intake found in heat-exposed rats. Heat-exposed rats showed slower delayed-type hypersensitivity responses to keyhole limpet hemocyanin. They showed lower counts of peripheral blood total T cells (OX19+) as well as helper T cells (W3/25+) and smaller numbers of splenic T cells. The thymus was decreased in size. Increased levels of serum IgG antitetanus toxoid antibodies were found in heat-exposed rats. [3H]-thymidine incorporation into Concanavalin A (ConA)-stimulated splenic lymphocytes was decreased in pair-fed rats but not significantly altered in heat-exposed rats compared with controls. Heat exposure alters some aspects of both cellular and humoral immune function in a manner different from that induced by comparable food restriction without heat exposure.     

Small-bowel bacterial overgrowth and systemic immunosuppression in experimental peritonitis

The effect of intraperitoneal infection on small-bowel flora and on systemic immunity was studied in a rat model, with use of the delayed-type hypersensitivity (DTH) response to keyhole limpet hemocyanin (KLH) as a measure of global immunologic integrity. Twenty-four hours after the induction of peritonitis by cecal ligation and puncture, concentrations of Escherichia coli in the proximal gastrointestinal tract increased from fewer than 10(3) colony-forming units (CFU)/ml to more than 10(9) CFU/ml, and the DTH response decreased from 10.0 +/- 0.2 to 2.1 +/- 0.4 mm. To assess the contribution of this altered luminal flora to the observed suppression of DTH scores, cecal ligation without puncture was performed in a group of animals whose endogenous flora had been suppressed by administration of oral neomycin. Oral administration of live antibiotic-resistant E. coli to the study animals resulted in significant DTH depression compared with controls given saline solution (2.7 +/- 0.4 vs 4.4 +/- 0.4 mm, p less than 0.005), even though the gastrointestinal tract was anatomically intact. Similar depression was seen if the challenge was limited to the small bowel as a result of the prior performance of an ileostomy and occurred in the absence of significant systemic or portal levels of viable bacteria. The results suggest that gut endotoxin plays a role in the immunosuppression associated with peritonitis.     

Epoxide hydratase: sex specific expression and rate-limiting role in DMBA metabolism

The rate of generation of the proximate carcinogen 7,12-dimethylbenz[a]anthracene 3,4-dihydrodiol (DMBA 3,4-diol) from DMBA, was 3-fold lower in rat liver microsomes (RLM) from female, compared to male Sprague-Dawley rats. However, the sum of products that potentially derive from the common intermediate DMBA 3,4-oxide namely, DMBA 3,4-diol, 3- and 4-hydroxy DMBA, was comparable between the two sexes (18 versus 20 pmol/mg/min). Addition of purified microsomal epoxide hydratase (EHm) (150 nM) to female RLM increased the rate of DMBA 3,4-diol formation to a level comparable to that obtained in male RLM. This activity was not increased when equivalent amounts of EHm were added to male RLM. Female RLM contained 2-fold lower levels of EHm protein compared to male RLM, based on Western blot analyses, and exhibited correspondingly lower hydrating activities towards both benzo[a]pyrene 4,5-oxide (BP 4,5-oxide) and DMBA 5,6-oxide. The rate of DMBA 3,4-diol formation was also limited by the availability of EHm in lung and adrenal microsomes from male rats. Addition of exogenous EHm to both tissues stimulated DMBA 3,4-diol formation by 2 and 6-fold respectively. EHm activity was still more deficient in the formation of the K-region, DMBA 5,6-diol, and this limitation was seen in both female and male-RLM as well as in microsomes from extrahepatic tissues. These limiting effects were enhanced by 3-methylcholanthrene treatment, through increases in DMBA monooxygenase but not EHm activities, but were diminished by phenobarbital treatment where EHm was also induced. Manipulation of EHm activity (through addition of pure EHm or its inhibitor trichloropropylene oxide) demonstrated a direct relationship between EHm activity and total DMBA metabolism. A deficiency in EHm apparently caused a selective loss of products resulting from initial DMBA 5,6- and 8,9-monooxygenation. Substantial reduction of DMBA 5,6-oxide to DMBA was measured in RLM under anaerobic conditions. This reduction was inhibitable by ambient oxygen levels. These data indicate that insufficient cellular EHm levels result in the reversion of microsomally generated DMBA 5,6-oxide (and 8,9-oxide) back to DMBA and also lead to reduced activation of DMBA via the carcinogenic bay region diol epoxide.