[Relationship between cellular immune response and apoptosis of the brain neurons after brain trauma in rats].

ABSTRACT

OBJECTIVE: To investigate the relation between CD4(+) and CD8(+) T lymphocyte infiltration and apoptosis of the neurons in the local traumatic brain tissue after brain trauma in rats. METHODS: In rat models of brain trauma, the changes in the number of CD4(+) and CD8(+) T lymphocytes and the apoptosis of neurons in the local traumatic brain tissue were observed by immunohistochemistry at different time points after brain trauma. RESULTS: Twenty-four hours after brain trauma, a significant increase in the number of CD4(+) and CD8(+) T lymphocytes occurred in the injured brain tissue, both reaching the highest levels on day 10, at the point of which the number of CD4(+) cells increased by about 15 folds and that of CD8(+) cells by about 20 folds compared with the control groups. The CD4(+) and CD8(+) T lymphocytes both began to decrease 30 days after the injury. A similar pattern of alterations was found in the apoptosis of neurons in the local brain tissue. Correlation analysis demonstrated a close positive correlation between the changes in CD4(+) and CD8(+) lymphocyte numbers and the number apoptotic neurons in the injured brain tissue. CONCLUSIONS: Brain trauma induces obvious increases in CD4(+) and CD8(+) T lymphocytes and enhanced cellular immune response in the injured brain tissue to mediate neuronal apoptosis and further exacerbate the brain tissue injuries.