Zinc induces thymulin secretion from human thymic epithelial cells in vitro and augments splenocyte and thymocyte responses in vivo.
Zinc is incorporated into zinc-thymulin by the thymus and in this form is a critical hormonal regulator of cellular immunity. In the absence of serum, zinc induces human thymic epithelial cells (TEC) to secrete a factor which promotes the expansion of interleukin-2 (IL-2) receptor positive human peripheral blood lymphocytes in response to a low dose of phytohemagglutinin (PHA). This factor is removed by antithymulin antisera plus filtration and is thus presumed to be zinc-thymulin. Intraperitoneal treatment of hydrocortisone treated aged mice with zinc-thymulin (100 ng/day x 5) resulted in mild augmentation of splenocyte but not thymocyte responses in vitro to IL-1, IL-2, and natural cytokine mixture (NCM) and to PHA and concanavalin A (Con A) (average increase 40%). Like zinc-thymulin treatment, oral ingestion of zinc (72 micrograms/day x 5) resulted in augmentation of splenocyte IL responses; in contrast, it augmented thymocyte responses to all stimuli (average increase 100%). These preliminary experiments indicate that treatment with zinc may have immunotherapeutic relevance, particularly in the aged and stressed organism.
Saha
A R
AR
Department of Internal Medicine, University of South Florida Medical College, Tampa 33612, USA.
Hadden
E M
EM
Hadden
J W
JW
D000284:Administration, Oral; D000375:Aging / Q000276:immunology; D002478:Cells, Cultured; D004847:Epithelial Cells; D006801:Humans; D007167:Immunotherapy; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D013154:Spleen / Q000166:cytology / Q000187:drug effects*; D013935:Thymic Factor, Circulating / Q000187:drug effects* / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D015032:Zinc / Q000008:administration & dosage / Q000494:pharmacology*
D015375:Receptors, Interleukin-2; D013935:Thymic Factor, Circulating; D015032:Zinc