title: Modulation of early B lymphopoiesis by interleukin-3.
abstract: We recently reported that interleukin-3 (IL-3) inhibits B lymphoid lineage expression in methylcellulose culture in a dose-dependent manner. We subsequently used flow cytometric analysis of individual colonies in timed exposure to IL-3 to define more precisely the negative regulatory role of IL-3 in early B lymphopoiesis. When lymphohematopoietic progenitors isolated from 5-fluorouracil (5-FU)-treated mice were cultured in the presence of Steel factor (SF), IL-11, IL-7, and erythropoietin (Epo), B lymphopoiesis appeared to proceed through three stages: lymphohematopoietic proliferation, commitment, and early B lymphoid proliferation. When IL-3 was added to the culture for a 48-hour interval from days 4 to 6 of culture, IL-3 slightly enhanced the formation of pre-B cell colonies. These data appeared to contradict our previous observations that continued exposure to IL-3 from days 0 to 4 or longer severely inhibits B lymphoid potential of the cultured cells. A more frequently timed kinetic observation revealed that in the presence of IL-3 the peak of lymphohematopoietic progenitors was 48 hours earlier but less than one-tenth the number of lymphohematopoietic progenitors in cultures without IL-3. When added to cultures for 48 hours beyond day 6 of culture, IL-3 abrogated the B cell potential of the cultured cells. However, IL-3 failed to negatively modulate B lymphoid progenitors when added on day 14 of culture or later. These observations indicate that IL-3 is a potent negative modulator of the early B lymphopoiesis. IL-3 appears to hasten but suppress the proliferation and commitment of lymphohematopoietic progenitors to B cell lineage. It may also inhibit the proliferation of the progenitors immediately after commitment to B cell lineage.
authors.affiliation: Department of Medicine, Medical University of South Carolina, USA.
authors.forename: T C
authors.initials: TC
authors.lastname: Ball
authors.forename: F
authors.initials: F
authors.lastname: Hirayama
authors.forename: M
authors.initials: M
authors.lastname: Ogawa
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology* / Q000187:drug effects / Q000276:immunology; D001854:Bone Marrow Cells; D016466:CHO Cells; D002454:Cell Differentiation; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D006224:Cricetinae; D004921:Erythropoietin / Q000494:pharmacology; D005434:Flow Cytometry; D005472:Fluorouracil / Q000494:pharmacology; D006410:Hematopoiesis / Q000187:drug effects*; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000276:immunology; D006801:Humans; D017370:Interleukin-11 / Q000494:pharmacology; D007377:Interleukin-3 / Q000494:pharmacology*; D015851:Interleukin-7 / Q000494:pharmacology; D051379:Mice; D011994:Recombinant Proteins / Q000494:pharmacology; D019089:Stem Cell Factor / Q000494:pharmacology
chemical_list: D017370:Interleukin-11; D007377:Interleukin-3; D015851:Interleukin-7; D011994:Recombinant Proteins; D019089:Stem Cell Factor; D004921:Erythropoietin; D005472:Fluorouracil