Thymosin stimulates interleukin-6 production from rat spleen cells in vitro.
Thymosin fraction 5 (TF5) is a partially purified preparation of bovine thymus that affects the differentiation and function of T-cells in vitro. Interleukin-6 (IL-6) is a pleiotropic cytokine that induces terminal maturation of B-cells and T-cell activation and differentiation. Although TF5 had previously been shown to stimulate the production of a number of lymphokines, its effects on IL-6 were not known. In this study we determined the effect of TF5 on IL-6 production from rat spleen cells in vitro. TF5 (100 micrograms/ml) stimulated IL-6 production from splenocytes (0.75-3.0 x 10(5) cells/well) in the presence of 0.008-0.2 micrograms/well of the T-cell mitogen concanavalin-A (con-A) by 10-20 fold during a 72 h incubation period. Dose-response studies demonstrated that 10 micrograms/ml of TF5 was the lowest concentration capable of enhancing IL-6 production. The ability of TF5 to stimulate IL-6 production in the presence of con-A could be demonstrated within 24 h of incubation; longer incubation periods (48-72 h) correlated with further enhancements of IL-6 production. Partial purification of the IL-6-inducing activity from TF5 resulted in three subfractions possessing activity in the presence of con-A (MB2, MB3, MB7) and one in the absence of con-A (MB2). The previously characterized thymosin peptides T alpha 1 and T beta 4 had no effect on IL-6 production in the absence or presence of mitogen. This study reports a new biological activity for TF5 and suggests that a novel constituent of TF5 may enhance the production of IL-6 from spleen cells.
Attia
W Y
WY
Department of Physiology, Medical University of South Carolina, Charleston 29425.
Badamchian
M
M
Goldstein
A L
AL
Spangelo
B L
BL
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D004306:Dose-Response Relationship, Immunologic; D005786:Gene Expression Regulation / Q000187:drug effects; D015850:Interleukin-6 / Q000096:biosynthesis*; D016131:Lymphocyte Subsets / Q000187:drug effects / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D051381:Rats; D013154:Spleen / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D013268:Stimulation, Chemical; D000077596:Thymalfasin; D013947:Thymosin / Q000031:analogs & derivatives* / Q000494:pharmacology; D000099201:Thymosin beta(4)
D003208:Concanavalin A; D015850:Interleukin-6; D000077596:Thymalfasin; D013947:Thymosin; D000099201:Thymosin beta(4); C033782:thymosin fraction 5