Flow cytometric analysis of lymphocyte subpopulations after thermal injury in human beings

Several theories have been advanced in an effort to explain immunologic suppression after thermal injury, that is monocyte production of immunoregulatory prostaglandins, activation of suppressor cells, production of suppressive serum factors and alteration in helper cell function. In the current study, cytofluorometric analysis was performed on peripheral blood mononuclear cells isolated from 30 severely burned individuals using a FACS IV cell sorter. Fluorescein labeled monoclonal antibodies were used to phenotype total T cells (OKT3+), helper cells (OKT-4+), suppressor cells (OKT-8+), monocytes (antimono.2+) and B cells (anti-Ia+). After burn injury, the most striking phenotypic alterations observed were a marked decrease in the number and percentage of total OKT3+ T cells and OKT4+ helper cells. No significant increases were observed in the OKT8+ suppressor cell subpopulation. Monocytes exhibited a transitory increase during the first 48 hours postburn which returned to normal by postburn day 7. The percentage of Ia+ cells were either normal or decreased in number during the course of the injury. An OKT-4 to OKT-8 ratio of less than 1.00 at 24 to 48 hours postburn may represent a reliable predictive index for death by sepsis. These data suggest that the syndrome of burn induced immunologic suppression may be better described as a "burn induced immunodeficiency syndrome," that is characterized by decreased numbers or function of Interleukin-2 producing helper cells, or both.