Mechanism of impaired immunologic response to bacterial antigens in burn wounds in children

Material was obtained from necrotic tissue excised from burn wounds in 60 children and examined immunohistochemically for the percentages of CD3, CD4, CD8, CD20, and CD68 cells. The results were then correlated with the burn surface area (BSA). Bacteriologic studies revealed the presence of bacteria in only 22 wounds with BSA greater than 10% of total body surface area. In this group, the proportion of CD3, CD4, CD8, CD20, and CD68 cells was correlated with the severity of infection, measured as the number of bacteria per g tissue. The results showed a positive correlation between the BSA and the percentage of CD8 cells (P < 0.001) and a negative correlation between CD4 cells and BSA (P < 0.02). The correlation between CD4/CD8 index and BSA was significantly negative. Likewise, a significant negative correlation was also noted between the percentage of CD4 and CD8 cells within the wound (P < 0.001). The severity of infection (bacteria/g tissue) was also positively correlated with the percentage of CD8 cells (P < 0.05) and negatively with the percentage of CD4 cells (P < 0.05). The correlation between CD4/CD8 index and intensity of infection was also highly significant. The results obtained show that in extensive burn wounds bacterial antigens may not be recognized properly due to the decreased percentage of CD4 cells and increased percentage of CD8 cells, which enhances bacterial growth in these wounds.