The Relationship between the Percentage of Circulating B Cells, Corticosteroid Levels, and Other Immunologic Parameters in Thermally Injured Patients

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Abstract
Thermal injury is known to induce alterations in the immune system, but the precise mechanism have yet to be elucidated. We investigated the temporal relationship between serum and urine corticosteroid levels, the number of circulating B cells, serum immunoglobulin levels, and delayed hypersensitivity reactions in the postburn period. Fifteen adult patients (mean age, 44 years) admitted with thermal burns greater than 20% body surface area (BSA) (mean, 50%) were evaluated during four postburn periods. Using a bacterial adherence assay in blood smears, we observed an increased percentage of B lymphocytes (20.3%) in the early postburn period compared to normal controls obtained during the same time period (13.1%). The percentage of B cells gradualy decreased during the subsequent 4 weeks and was not influenced by the eventual clinical outcome. The changes in B-cell percentage were paralleled by changes in the level of urine 17-hydroxysteroids. Serum IgG concentrations were low during the initial postburn period in survivors and nonsurvivors and returned to normal and above-normal levels in the late postburn period in both groups. The delayed hypersensitivity skin test reactions were also depressed in the immediate postburn period and returned to normal only in the surviving group at the end of the second postburn week. We speculate that the increased endogenous secretion of stress hormones results in an increase in circulating B cells secondary to their release from lymphoid organs and that the normalization of hormone levels as wound healing ensued was associated with the return of B cells to the lymphoid organs. This lymphocyte redistribution may result in polyclonal cellular interactions, with subsequent B-cell activation, and increased IgG production.