Alterations in the immunologic response after a major trauma include:

a. Decreased CD3 and CD4 population

b. Depression of neutrophil antimicrobial functions including chemotaxis and phagocytosis

d. Impaired macrophage receptor expression and antigen presentation

Major perturbations in the immune system occur in patients after injury contributing to the late septic mortality in trauma patients. The changes in the immune system are significant and global, affecting both humoral and cellular components of the system. Macrophage receptor expression and subsequent antigen presentation are impaired with similar defects in lymphocyte function including shifts in T-cell populations with decreased CD3 and CD4 subpopulations, depression of B-cell and immunoglobulin production, and a loss of antigen recall. Multiple neutrophil antimicrobial functions are suppressed following trauma including chemotaxis, phagocytosis, respiratory bursts, and intracellular killing. There are significant changes in humoral mediators following trauma with increased levels of pro-inflammatory cytokines including tumor necrosis factor, interleukin-1 and interleukin-6 along with decreased levels of interleukin-2, interleukin-3, and interferon g