Avian hematopoiesis in response to avian cytokines

The objective of this study was to examine the hematopoietic cell proliferation and differentiation potential of growth factors produced by chicken macrophages. Bone marrow (BM) cells (25 x 10(3)) from newly hatched B15B15 K-strain Leghorn chicks were seeded in .5 mL serum-free semi-solid culture supplemented with 10% (vol/vol) of a conditioned medium (CM) from a chicken macrophage cell line, MQ-NCSU. The conditioned medium was obtained by culturing MQ-NCSU cells either in LM-HAHN (CMI) or RPMI-1640 (CMII) growth medium. The control cultures contained only LM-HAHN or RPMI medium. Bone marrow cells in the presence of CMI differentiated predominately into granulocyte colonies (Experiment 1 = 84 +/- 9.2; Experiment 2 = 105 +/- 5). No colonies were observed in the control cultures. Stimulation of MQ-NCSU cells with lipopolysaccharide (LPS) produced a CM that differentiated BM cells predominantly into macrophage colonies (122 +/- 16.3 in CMI and 92 +/- 5.6 in CMII). These data suggest that MQ-NCSU cells spontaneously secrete a factor with the potential to promote granulocyte differentiation. However, upon stimulation with LPS, the factor secreted had macrophage colony stimulation potential (M-CSF), which was similar in activity when compared with the activity of recombinant chicken myelomonocytic growth factor (r-cMGF). Another CM from chicken fibroblasts (FCM) was tested on BM cells from K-strain Leghorns and Arbor Acres x Arbor Acres broiler chicks. Data from three experiments showed that 25 x 10(3) BM cells from K-strain chicken yielded more macrophage and granulocytes colonies (82 +/- 14) than those from broilers (56 +/- 12). This study suggests that avian cytokines exhibit progenitor cell differentiation potential and that this activity is dependent upon the source of cytokines and their targets.