| Oligopeptides and low molecular weight polypeptides play central roles as effectors and signal transducers acting as hormones, neurotransmitters, growth factors, toxins, and antimicrobial factors that are important for the survival of the organism. Owing to the ubiquitous involvement of peptides in many key regulatory processes, we have been interested to identify native peptides in different cells and tissues and understand their functions. To conduct our studies, we used avian macrophages and heterophils as models of specialized cells which constitute central components of innate immunity. These studies involved (a) qualitative identification and characterization of the peptides associated with high intensity mass spectral peaks in macrophage and heterophil and (b) the quantitative changes in those peptides under immunomodulating effects of toll-like receptor (TLR) activators. The work presented here describes the identification of thymosin beta 4 (Tbeta4), an actin binding peptide, in macrophages and its modulation under TLR activation. This dissertation also includes identification of mature avian beta defensin 2 (AvBD2), an antimicrobial peptide in heterophils of 4 different avian species (chicken, turkey, pheasant and quail) and its modulation in chicken heterophils under similar conditions. |
