The effects of anesthesia and surgery on lymphocyte populations and function in infants and children.

A study was designed to test the hypothesis that the lymphopenia caused by surgical stress in children may arise through selective depletion of one or more lymphocyte subsets. Blood samples from 22 children were taken pre- and postoperatively and 6, 12, 24, and 48 hours after surgery. Lymphocyte subsets were identified and counted using monoclonal antibodies and indirect immunofluorescence. By six hours postoperatively, the mean total lymphocyte count had fallen by 1.87 x 10(9)/L (P less than .01); this was largely due to the fall in helper T cells (1.53 x 10(9)/L, P less than .01) and both counts remained depressed for at least 48 hours. The helper:suppressor ratio also fell, from 3.42 to 1.92 (P less than .01), but had recovered by 48 hours. Lymphocyte function as measured by the response to pokeweed mitogen and concanavalin A was also reduced six hours postoperatively. These changes were independent of age. Major surgery in infants and children causes a selective reduction in helper T lymphocyte numbers, helper:suppressor ratio, and lymphocyte function. This suggests that immune competence in the immediate postoperative period in children is reduced, as it is in adults. The duration of this and its relationship to infection are not yet known.