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The thymus is the organ where T lymphocytes mature. Its involution with age —it shrinks and is replaced by fat from adolescence onward— is one of the hallmarks of immunosenescence and has motivated the study of thymic peptides.
Timosina α1
- A 28-amino-acid peptide that enhances the maturation and function of T lymphocytes and dendritic cells.
- It is the thymic peptide with the most clinical development: it was approved in several countries (under the brand Zadaxin) as an adjuvant in hepatitis B and C and in some immunodeficiency settings. It does not have FDA approval.
Thymosin β4: similar name, different function
Despite its name, thymosin β4 is not a thymic hormone in the functional sense: it is a protein that sequesters actin and is found in almost all tissues. Its relevance is tissue repair (repair module), not immunomodulation. Confusing them is a common error in popular literature.
Thymic extracts (thymalin)
Thymalin is an extract of thymus peptides developed in the Soviet and Russian clinical tradition. The literature, mostly from those groups, describes effects on lymphocyte subpopulations and aging markers. As with the other bioregulators of that school, independent replication is scarce, and the chemical characterization of an extract is inherently less precise than that of a synthetic peptide with a defined sequence.
| Compound | Nature | Main function |
|---|---|---|
| Thymosin α1 | Defined synthetic peptide | Immunomodulation of T lymphocytes |
| Thymosin β4 | Ubiquitous protein | Actin dynamics and repair |
| Thymalin | Peptide extract | Immunomodulation (Russian literature) |
Catalogue compounds mentioned in this lesson
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