Effects of thyroid hormone deprivation on immunity in postmetamorphic frogs.
Previously, we showed that sodium perchlorate treatment of larval frogs (Xenopus laevis) interferes with the normal expansion of T and B lymphocytes and development of an adult-type T-cell population. It was unclear whether these effects resulted from preventing metamorphosis or from long-term thyroid hormone (TH) deprivation. To try to distinguish between these possibilities, we have now studied the effects of perchlorate treatment beginning immediately after metamorphosis. After 5 months, treated animals, but not untreated controls, had large thyroid goiters, were significantly smaller, and had significantly fewer erythrocytes, thymocytes, and splenocytes. Although the number of IgM- splenocytes and thymocytes was reduced, the estimated percent of major histocompatibility complex (MHC) class II+ cells within this subset was not significantly different from that of controls. Furthermore, splenocytes from perchlorate-treated frogs could respond normally by [3H]TdR incorporation to the T-cell mitogens, phytohemagglutinin-P (PHA) and concanavalin A (Con A). Thus, unlike perchlorate-treated larvae, perchlorate-treated juveniles appear to be able to develop T cells with an adult phenotype competent to respond to activation and proliferation signals.
Department of Microbiology & Immunology and Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232.
L A
LA
Rollins-Smith
A T
AT
Davis
P J
PJ
Blair
D000818:Animals; D004920:Erythropoiesis / Q000187:drug effects; D006042:Goiter / Q000139:chemically induced / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D007037:Hypothyroidism / Q000139:chemically induced / Q000150:complications / Q000276:immunology*; D007075:Immunoglobulin M / Q000032:analysis; D007153:Immunologic Deficiency Syndromes / Q000209:etiology*; D016131:Lymphocyte Subsets / Q000187:drug effects*; D008675:Metamorphosis, Biological; D010472:Perchlorates / Q000633:toxicity; D011947:Receptors, Antigen, B-Cell / Q000032:analysis; D017670:Sodium Compounds; D013963:Thyroid Hormones / Q000502:physiology*; D014982:Xenopus laevis / Q000254:growth & development / Q000276:immunology*
D000949:Histocompatibility Antigens Class II; D007075:Immunoglobulin M; D010472:Perchlorates; D011947:Receptors, Antigen, B-Cell; D017670:Sodium Compounds; D013963:Thyroid Hormones; C031068:sodium perchlorate