Growth hormone-like factor produced by the tapeworm, Spirometra mansonoides, displaces human growth hormone (hGH) from its receptors on cultured human lymphocytes
An analogue of hGH isolated from plerocercoids of the tapeworm Spirometra mansonoides displaces (/sup 125/I)hGH from its receptors in rabbit, rat, and hamster liver membranes. Biologically, plerocercoid growth factor (PGF) is more similar to hGH than to other mammalian GH's but has not been shown to bond human cells. Receptors specific for hGH have been described on cultured human lymphocytes (IM-9). In this study, the authors compared the binding of PGF and hGH in IM-9 cells and in rabbit hepatic membranes. IM-9 lymphocytes (12 x 10/sup 6/ cells/tube) were incubated with (/sup 125/I)hGH and increasing concentrations of hGH (ng/ml) or PGF (serial dilutions) for 90 min at 30/sup 0/ C. Specific binding (B/sub 0/ - NSB) was determined for each dose of hGH or PGF and the binding curves were analyzed by logit-log regression. The results show that PGF displaced (/sup 125/I)hGH from human cells in a dose dependent manner (r = 0.98). Based on the IM-9 assay, 1 ml of the PGF had an activity equivalent to 625 ng of the hGH standard (ngE). However, the binding activity of the PGF in the rabbit liver RRA was 1653 ngE/ml, indicating that the binding potency of PGF in IM-9 cells was only 38% of that in the rabbit liver. These results clearly demonstrate that PGF binds hGH receptors in cells of human origin, suggesting that PGF will be effective in humans.
- Research Organization:
- Univ. of Nebraska Medical Center, Omaha
- OSTI ID:
- 5386015
- Report Number(s):
- CONF-8604222-; TRN: 86-026547
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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550201* - Biochemistry- Tracer Techniques