Colony forming units in culture and colony stimulating activity of systemic lupus erythematosus.

The bone marrow granulocyte-macrophage progenitor cells (CFU-C) in patients with systemic lupus erythematosus (SLE) were estimated according to the double-layer soft agar system of Pike and Robinson. When nucleated narrow cells from patients with SLE were cultured with peripheral leukocytes from normal donors as a source on colony stimulating activity (CSA), colony counts (the term colony indicating aggregates of more than 50 cells) in active SLE were reduced significantly but cluster counts (cluster: 10 to 50 cells) were divided into two groups of markedly increased and decreased clusters. When normal nucleated marrow cells were cocultured in the overlayer with peripheral leukocytes of patients with SLE in he feeder layer, colony counts decrease significantly but cluster counts remained within the normal range. When CFU-C by normal nucleated marrow cells were studied in the presence of PHA- or LPS-induced CSA of peripheral leukocytes from patients with SLE, total colony and cluster counts decreased. These data indicate the granulomonocytopenia in SLE may result from the diminution of production of CSA in peripheral leukocytes and/or the direct impairment of growth and differentiation in progenitor cells of granulocytes and macrophages.