Impact of in ovo-administered lead and testosterone on developing female thymocytes.
The developing immune system is particularly sensitive to lead-induced immunotoxicity, but in some models, genders can differ in lead-induced immunotoxicity. Using an avian in ovo model of lead-induced T-helper disruption, the ability of in ovo administered lead and testosterone to alter thymocyte maturation among female embryos was investigated. On embryonic day (E) 8, Cornell K-strain embryos were given either testosterone (12.5 microg/egg in ethanol) or 15% ethanol in 100 microl volume. The groups then received either lead acetate (200 microg/egg) or sodium acetate (control) on E 12 of incubation. On E 20, thymocytes from 4-5 female embryos per group were analyzed by flow cytometry for cell surface markers CD3, CD4, CD8, TCR1, and TCR2. Lead alone did not induce any appreciable changes among the cell populations measured in this study. However, when testosterone treatment was followed by lead (testosterone + lead), there was a significant increase in CD4+CD8+ double-positive cells compared with either control or lead treatment groups. Testosterone, either by itself or in combination with lead, significantly reduced the percentage of cells with the CD4+CD8- phenotype when compared to the lead alone group. No change was detected with respect to the CD4-CD8+, CD4-CD8-, TCR1+, and TCR2+ phenotypes following any treatment. Therefore, sex hormonal balance in early life appears to influence the manner in which the developing thymus responds to the heavy metal lead.
Hussain
Irshad
I
Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
Piepenbrink
Michael S
MS
Dietert
Rodney R
RR
D000818:Animals; D018791:CD4 Lymphocyte Count; D016827:CD8 Antigens; D002642:Chick Embryo; D005260:Female; D005434:Flow Cytometry; D007854:Lead / Q000633:toxicity*; D008297:Male; D013739:Testosterone / Q000494:pharmacology*; D013950:Thymus Gland / Q000187:drug effects / Q000254:growth & development / Q000276:immunology*
D016827:CD8 Antigens; D007854:Lead; D013739:Testosterone