The effects of major and minor trauma on lymphocyte kinetics in mice.

The effects of major and minor trauma on the circulating white blood cell populations of C57BL mice were followed. The results showed that not only major trauma (nephrectomy) but minor injury and stress (e.g. injection, bleeding) triggered a highly significant fall (50-70%) in the number of lymphocytes circulating in the blood. The fall was a gradual one, with the maximal drop 2 h after the operation or handling procedure. Major trauma resulted in a fall in both B and T lymphocytes. Minor trauma produced a fall in B lymphocytes only. A 3-4 fold increase in circulating polymorph numbers also accompanied major trauma, but no increase was observed after minor trauma. The blood picture returned to normal generally within 24 h of both minor and major trauma. Repetition of the trauma stimulus after recovery led to a renewed trauma response. Bilateral adrenalectomy abolished the lymphocyte response to major and minor trauma and decreased the polymorph response to major trauma by more than 50%, indicating that stress hormones played a role in these changes. Studies with 51chromium-labelled lymphocytes, transferred into traumatized and adrenalectomized animals, suggested that decreased entry of lymphocytes into the blood (rather than increased exit from the blood into the tissues, or cell death) was the most likely mechanism of the lymphopenia following trauma.