Inhibitory effect of glycosaminoglyeans isolated from peripheral blood granulocytes of patients with chronic myeloleukemia and normal subjects on increment in colony-forming units of fibroblasts in monolayer cultures of rat bone marrow is determined by the degree of sulfation of their main component ehondroitin-4-sulfate and by increased content of heparan sulfate. Key Words: glycosaminoglycans; increase in the number of colony-forming units of bone marrow fibroblastsGlycosaminoglycans (GAG) and their conjugates with proteins proteoglycans are the major components of the extracellular matrix of bone marrow. Human bone marrow stromal cells produce ehondroitin-6-sulfate (C-6-S), dermatan sulfate, and heparan sulfate that participate in cell-to-cell reactions with stem cells and hemopoiesis precursor cells, determining their adhesion, migration, proliferation, and differentiation [4,6]. On the other hand, bone marrow and blood hemopoietic cells contain GAG in the form of proteoglycans and free polysaccharide chains. The major component of granuloeytic GAG is polydispersed C-4-S, while heparan and dermatane sulfates are minor components [5]. Activation of hemopoietic cells is associated with intense production and secretion of GAG functioning as mediators, reacting with bone marrow stromal elements [4,5]. However, the mediator role of hemopoietie cell GAGs has not been evaluated. We revealed the ability of GAG isolated from human blood granuloeytes to modify pro- MATERIALS AND METHODSExperiments were carried out in rat bone marrow monolayer cultures [2]. Bone marrow cells were isolated from femoral bone of Wistar rats weighing 200-250 g. The cells (0.5-5.0x 106) were expanded in Carrel's flasks (25 cm 2) in RPMI-1640 (Sigma) with 15% fetal calf serum in an atmosphere with 5% CO,. Nonadherent bone marrow cells were removed after 48 h, then GAG in a concentration of 1-5 I~g uronic acids/ml and chondroitin sulfates (0.5, 1, 10, and 30 ps/ml) were added. Two fractions of low-and sulfated GAGs were used They were isolated by the papain method [3] from acetone-dried blood granulocytes from patients with CML during the chronic 0007-4888/98/0003-0282520.00 elgg8 Plenum .Publishing Corporation