Haematological changes and free-radical involvement in an experimental foot-pad oedema model

Abstract

A foot-pad oedema model was used to investigate some early peripheral blood changes associated with the development of an acute inflammatory response. The inflammatory model used was an example of a cell-mediated hypersensitivity reaction. Male rats were inoculated in the scruff with Freund's Complete Adjuvant (FCA) on day 0 and then challenged 6 days later with FCA in one hind paw. An acute inflammatory reaction was initiated over the following 72 hours. Within 8 hours of induction a significant increase in neutrophils was detected in the peripheral blood reaching peak levels at 24 hours. The peak level of monocytes was not seen until 48 hours after challenge. Lymphocyte numbers, haemoglobin and haematocrit values all remained within the normal range. Plasma iron levels fell by approximately 85% within 24 hours whereas plasma α-1-acid glycoprotein and the copper-containing protein caeruloplasmin were found to increase steadily throughout the development of the inflammatory response. These findings are discussed in relation to previously published work using the same model. An important inter-relationship between phagocytic cells, iron and free radical production at the site of the acute inflammatory reaction is suggested.