Thymosin Beta in Macrophage

Thymosin, originally discovered as a thymic hormone regulating maturation of T cells, is found in many hematopoetic and non-hematopoetic tissues including bone marrow, spleen, and lungs. While studying chicken monocyte- and granulocyte- associated peptides by Matrix Assisted Laser Desorption Ionization/ Time-of-Flight (MALDI-TOF) mass spectrometry, we found a peptide corresponding to mass/charge ratio (m/z) of 4963. This peptide was prominently associated with monocytes but not with the granulocyte population. Experiments revealed presence of this peptide in chicken macrophage cell lines. We purified the 4963Da peptide from the macrophages by reverse phase HPLC and identified it as thymosin β4 (Tβ4) by peptide mass fingerprinting. Tβ4 binds to G- actin, and regulates its polymerization, which is essential for cell motility. Besides, it is also involved in a multitude of other functions regulating immunity and wound healing. This review surveys the physiological significance of Tβ4 in relation to macrophage function.