CLONAL ORIGIN OF HUMAN BASOPHIL MAST-CELLS FROM CIRCULATING MULTIPOTENT HEMATOPOIETIC PROGENITORS

Abstract

The origin of the human basophil/mast cell lineage from a pluripotent hematopoietic stem cell has been surmised but never demonstrated. By examining individual hemopoietic colonies in methylcellulose under inverted microscopy and using histochemical stains in conjunction with single-colony histamine assays, basophil/mast cell progenitors were previously identified in human peripheral blood. A large proportion of normal human peripheral blood mixed granuloerythropoietic (GEMM) colonies contain histamine, in contrast to a significantly lower frequency of histamine positivity among normal neutrophil-macrophage, eosinophil, erythroid, macrophage, or megakaryocyte colonies. Morphological observations showed the presence of basophil/mast cells in the majority of GEMM colonies. The clonal derivation of basophils/mast cells from circulating multipotent (CFU-GEMM) hemopoietic stem cells was formally demonstrated, using combined histamine and G6PD [glucose-6-phosphate dehydrogenase] isoenzyme analysis of single colonies grown in methylcellulose from a normal G6PD heterozygote.