The lipid peroxidation product 4-hydroxynonenal (HNE) and homologous aldehydes have been found to possess chemotactic activity for rat neutrophil leukocytes in the micromolar to picomolar range, depending on the compound. Such an activity is displayed only in the presence of albumin. The mechanisms by which aldehydes could interact with neutrophils are discussed. It is proposed that albumin acts as a carrier for the aldehyde and releases them to a neutrophil receptor. At concentrations around 10(-4) M, 4-hydroxyalkenals have been found to exert toxic effects on a number of cells, including a strong depression of neutrophil motility VSports手机版. Finally, HNE has been found at chemotactic concentrations in the inflammatory site. The possibility that HNE is involved in the neutrophil influx into the inflammatory site is considered. .