AVIAN HEMATOPOIESIS IN RESPONSE TO AVIAN CYTOKINES

The objective of this study was to examine the hematopoietic cell prol iferation and differentiation potential of growth factors produced by chicken macrophages. Bone marrow (BM) cells (25 x 10(3)) from newly ha tched (BB15)-B-15 K-strain Leghorn chicks were seeded in .5 mt serum-f ree semi-solid culture supplemented with 10% (vol/vol) of a conditione d medium (CM) from a chicken macrophage cell line, MQ-NCSU. The condit ioned medium was obtained by culturing MQ-NCSU cells either in LM-HAHN (CMI) or RPMI-1640 (CMII) growth medium. The control cultures contain ed only LM-HAHN or RPMI medium. Bone marrow cells in the presence of C MI differentiated predominately into granulocyte colonies (Experiment 1 = 84 +/- 9.2; Experiment 2 = 105 +/- 5). No colonies were observed i n,the control cultures. Stimulation of MQ-NCSU cells with lipopolysacc haride (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, up on stimulation with LPS, the factor secreted had macrophage colony sti mulation potential (M-CSF), which was similar in activity when compare d with the activity of recombinant chicken myelomonocytic growth facto r (r-cMGF). Another CM from chicken fibroblasts (FCM) was tested on BM cells from K-strain Leghorns and Arbor Acres x Arbor Acres broiler ch icks. Data from three experiments showed that 25 x 10(3) BM cells from K-strain chicken yielded more macrophage and granulocytes colonies (8 2 +/- 14) than those from broilers (56 +/- 12). This study suggests th at avian cytokines exhibit progenitor cell differentiation potential a nd that this activity is dependent upon the source of cytokines and th eir targets.