Abstract: AIM: To explore the contribution of serum without immunoglobulin G from patients with systemic lupus erythematosus (SLE) associated throm-bocytopenia on megakaryocytopoiesis of stem cells de-rived from normal cord blood .METHODS: The im-munoglobulin G was depleted from serum of patients with SLE associated thrombocytopenia by Affinity Chro-matography .The mononuclear cells derived from nor-mal cord blood were cultured in semi-solid culture sys-tem in vitro in presence of thrombopoietin (TPO) . Colony forming units-megakaryocyte (CFU-MK) was quantified by an indirect immunophosphatase alkaline labeling technique using an anti-GP Ⅱb/Ⅲa MoAb. RESULTS: No statistically difference can be found be-tween the number of CFU-MK (69.3 ±19 .4) in nor-mal control(n =10) and the group(n =4) with addit-ional serum from SLE patients with thrombocytopenia or without immunoglobulin G (58.5 ±32.5 vs 73.0 ± 28.3, P >0.05) Suppression of megakaryocyto-poiesis, however, could be observed only in one case after addition of serum, and the suppression did not disappear when immunoglobulin G was depleted from the serum by Affinity Chromatography .Morphological-ly, the large colony could be observed in normal cord blood, while almost all of colony was small after addit-ion of serum of patients (13.9±3 .9 vs 34.0±12.6, P<0.05) or without immunoglobulin G (13.9 ±3.9 vs 43.8 ±15.4, P<0.05) compare to normal con-trol .CONCLUSION: It may suggest that the serum from patients with SLE associated thrombocytopenia could suppress the formation of CFU-MK derived from normal cord blood.The suppression might be indepen-dented on immunoglobulinG .

Key words: lupus erythematosus, systemic, thrombocytopenia, megakaryocytopoiesis