Diminished thymosin alpha-1 levels in persons exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin.
There is evidence from animal studies that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) impairs immune responses, with the thymus being a principal target organ. The purpose of this study was to evaluate thymic function, through measurement of thymic hormone levels, in persons exposed to TCDD. We examined thymosin alpha-1 (Thya-1) levels in sera from a group of 94 persons who were presumed to be exposed to TCDD from living, working, or recreating in a contaminated residential area. We compared these results, along with results from in vitro and in vivo tests of immune function, with those from a group of 105 unexposed persons who were similar with regard to age, sex, and race. The exposed group had a significantly lower mean Thya-1 serum level (977.3 +/- 304.1 pg/ml vs. 1148.7 +/- 482.1 pg/ml, p less than .01 by t-test). We also found a statistically significant trend of decreasing Thya-1 levels with increasing number of years of residence in the TCDD-contaminated area. However, Thya-1 levels were not associated with other measures of immune function in the TCDD-exposed group. Thus, while the principal findings suggest that long-term TCDD exposure may be associated with diminished secretion of Thya-1, the lack of an association with an increased prevalence of clinically diagnosed immune suppression in these TCDD-exposed persons makes the biologic significance of the findings unclear. Further studies are needed to more fully evaluate possible long-term TCDD-induced effects on the thymus and human immune function.
Stehr-Green
P A
PA
Centers for Disease Control, Atlanta, GA 30333.
Naylor
P H
PH
Hoffman
R E
RE
D000367:Age Factors; D000818:Animals; D004147:Dioxins / Q000009:adverse effects*; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007109:Immunity / Q000187:drug effects; D008297:Male; D051379:Mice; D000072317:Polychlorinated Dibenzodioxins / Q000009:adverse effects*; D044469:Racial Groups; D012737:Sex Factors; D013601:T-Lymphocytes / Q000187:drug effects; D000077596:Thymalfasin; D013947:Thymosin / Q000097:blood; D013950:Thymus Gland / Q000187:drug effects
D004147:Dioxins; D000072317:Polychlorinated Dibenzodioxins; D013947:Thymosin; D000077596:Thymalfasin