EFFECT OF CHRONIC EXPOSURE TO LEAD ON IMMATURE RAT LEUKOCYTES

Two-week's exposure to lead caused a three-fold rise in the number of total leucocytes per mu L blood in immature rats. Blood eosinophils, l ymphocytes, monocytes and neutrophils increased significantly followin g lead exposure. There were no significant changes in band neutrophils . Of all leucocytes, eosinophils were the only cells that increased si gnificantly in 24h after estrogen treatment in lead-exposed animals. N o changes in the remaining leucocytes were detected as a result of est rogen treatment in lead exposed or non-exposed rats. Previous work on 1-week exposure showed that lead only affected blood neutrophils. The difference may be explained as a result of time-dependent events, such as a change in regulatory mechanisms including the regulation of horm one receptor levels, or the synthesis of protective agents against tox icity such as stress proteins, which may play a role in hormone action .