Alterations in lymphocyte function and relation to phospholipid composition after burn injury in humans

Objective: Lymphocyte functions are dependent on fatty acid composition of membranes, and impaired functions can predispose patients to infection after burn injury. The current study was designed to describe changes in lymphocyte-phospholipid composition and lymphocyte-related immune functions from early to late recovery time points after burn injury. Design: Prospective observational. Setting: Firefighter's Burn Treatment Center, University of Alberta Hospital, Edmonton, Alberta, Canada. Patients: Subjects (n = 10) with >10% total body surface burn area. Measurements and Main Results: Blood was drawn from subjects at specific time points (0 days to >50 days) after burn injury. Fatty acid composition of the major phospholipid classes of isolated lymphocytes was determined by using gas liquid chromatography. Lymphocyte phenotypes and proliferation ([H-3]-thymidine uptake and interleukin-2 and interferon-gamma production) in response to mitogens were determined. Lymphocyte phospho-lipid 20:4n-6 content was 30% to 60% lower early compared with late postburn time points (p < .001). Interferon-gamma production by stimulated cells was found to negatively correlate with n-3 content (r = .7, p = .008). The expression of CD25 on antigen-mature CD8+ cells was associated with higher proliferative responses (r = .88, p < .004). Proportion of CD8+ cells was lower, and the proportion of activated monocytes was higher early compared with late postburn (p < .05). Natural killer cell cytotoxicity was low early after burn and increased with recovery. Conclusions: The results of this preliminary study suggest that immune activation occurs between the second and third week after burn injury, which is associated with changes in 20:4n-6 and n-3 fatty acid content of lymphocyte phospholipid. This study suggests that there is release or impaired synthesis of 20:4n-6 early after burn injury that may be related to functional changes in immune cells.