Mammalian granulocyte-macrophage colony-stimulating factor receptor expressed in primary avian hematopoietic progenitors: lineage-specific regulation of proliferation and differentiation

Cytokines Studied in Carp (Cyprinus carpio L.) in Response to Important Diseases

Cytokines belong to the most widely studied group of intracellular molecules involved in the function of the immune system. Their secretion is induced by various infectious stimuli. Cytokine release by host cells has been extensively used as a powerful tool for studying immune reactions in the early stages of viral and bacterial infections. Recently, research attention has shifted to the investigation of cytokine responses using mRNA expression, an essential mechanism related to pathogenic and nonpathogenic-immune stimulants in fish. This review represents the current knowledge of cytokine responses to infectious diseases in the common carp (Cyprinus carpio L.). Given the paucity of literature on cytokine responses to many infections in carp, only select viral diseases, such as koi herpesvirus disease (KHVD), spring viremia of carp (SVC), and carp edema virus disease (CEVD), are discussed. Aeromonas hydrophila is one of the most studied bacterial pathogens associated with cytokine responses in common carp. Therefore, the cytokine-based immunoreactivity raised by this specific bacterial pathogen is also highlighted in this review.

TGF-beta cooperates with TGF-alpha to induce the self-renewal of normal erythrocytic progenitors: evidence for an autocrine mechanism

Simultaneous addition of both TGF-alpha and TGF-beta induces the sustained, long-term outgrowth of chicken erythrocytic progenitor cells, referred to as T2ECs from both chick bone marrow and 2-day-old chicken embryos. By analysis for differentiation antigens and gene expression, these cells were shown to represent very immature haematopoietic progenitors committed to the erythrocytic lineage. T2ECs differentiate into almost pure populations of fully mature erythrocytes within 6 days, when TGF-alpha and TGF-beta are withdrawn and the cells exposed to anaemic chicken serum plus insulin. Outgrowth of these cells from various sources invariably required both TGF-alpha and TGF-beta, as well as glucocorticoids. Proliferating, established T2ECs still require TGF-alpha, but are independent of exogenous TGF-beta. Using a TGF-beta-neutralizing antibody or expressing a dominant-negative TGF-beta receptor II, we demonstrate that T2ECs generate an autocrine loop involving TGF-beta during their establishment, which is required for sustained proliferation. Using specific inhibitors, we also show that signalling via Mek-1 is specifically required for induction and maintenance of cell proliferation driven by cooperation between the TGF-alpha and -beta receptors. These results establish a novel mechanism by which self-renewal of erythrocytic progenitors is induced and establish avian T2ECs as a new, quasi-optimal model system to study erythrocytic progenitors.