Cellular defense in critically ill surgical patients.

Area of Science:

• Immunology
• Critical Care Medicine
• Surgical Outcomes

Background:

• Cell-mediated immunity plays a crucial role in patient outcomes.
• Assessing immune function in critically ill patients is vital for prognosis.
• Surgical patients in the ICU present unique challenges for immune response evaluation.

Purpose of the Study:

• To investigate the relationship between cell-mediated immunity and mortality in critically ill surgical patients.
• To evaluate the predictive value of recall antigen testing for survival in the ICU.
• To explore potential mechanisms underlying immune dysfunction in this patient population.

Main Methods:

• Cell-mediated immunity was assessed using 4 recall antigens in 102 critically ill surgical patients.
• Patient reactivity (reactors vs. non-reactors) was correlated with mortality rates.
• In vitro lymphocyte responses to mitogens (concanavalin A, phytohemagglutinin, pokeweed) and chemotaxis of mononuclear and granulocyte cells were analyzed.

Main Results:

• Mortality was significantly lower in patients with positive recall antigen reactions (14%) compared to non-reactors (45%) (p < .01).
• Among non-reactors remaining in the ICU >7 days, conversion to reactivity correlated with a significant decrease in mortality (70% vs. 20%, p < .001).
• Lymphocyte response to concanavalin A was reduced, while responses to phytohemagglutinin and pokeweed mitogen were normal; chemotaxis showed a slight increase.

Conclusions:

• Intact cell-mediated immunity, as indicated by recall antigen reactivity, is associated with improved survival in critically ill surgical patients.
• Impaired T-cell function may contribute to the reduced immune response observed in non-reactors.
• Immune status assessment could offer prognostic insights for surgical patients in intensive care.