Immune responses of rats chronically fed subclinical doses of lead

The effects of chronic feeding of low levels of lead on various cells of the rat immune system have been investigated. In the presence of Con A and PHA, lead appears to increase blastogenesis up to approximately 5 weeks with activity approaching that of the unleaded control cells at 14 weeks. B cells responded with increased mitogenicity in the presence of LPS up to the time of termination of the experiment (14 weeks). Macrophage activity and number in the lead-fed rat showed consistent decrease and eventual morphological impairment. It is hypothesized that lead has mitogen-like activity but disruption of macrophage-T cell interaction occurs with time.