Production and differentiation of NK lineage cells in long-term bone marrow cultures in the absence of exogenous growth factors.
Neither lytic NK cells nor IL-2-responsive NK precursors were produced in myeloid (Dexter) long-term bone marrow cultures (LTBMC). However, when myeloid LTBMC were switched to lymphoid (Whitlock-Witte) conditions and reseeded ("recharged") with fresh bone marrow cells (BMC), nonadherent cells with NK lytic activity and NK 1.1+ phenotype were produced within 1-2 weeks without the addition of exogenous IL-2 to the cultures. NK- and T cell-depleted BMC proliferated extensively in switched cultures and in 2 weeks generated cells that lysed the NK target YAC-1 but not the LAK target P815. The presence of NK precursors in the cultures was confirmed by reculturing nonadherent cells harvested from recharged LTBMC in fresh medium containing 50 U rIL-2/ml. High levels of NK lytic activity were generated. Sequential expression of NK 1.1 and IL-2 responsiveness followed by lytic activity was demonstrated by harvesting cells early after recharge, prior to the appearance of lytic cells. Elimination of NK 1.1+ cells depleted the ability to respond to IL-2 in secondary culture. Our studies demonstrate that myeloid-to-lymphoid switched LTBMC support the proliferation and differentiation of NK lineage cells from their NK 1.1-, nonlytic progenitors in the absence of an exogenous source of growth factors.
Pollack
S B
SB
Department of Biological Structure, University of Washington, Seattle 98195.
Tsuji
J
J
Rosse
C
C
D000818:Animals; D001854:Bone Marrow Cells; D002454:Cell Differentiation; D002455:Cell Division; D002478:Cells, Cultured; D005260:Female; D066298:In Vitro Techniques; D007694:Killer Cells, Natural / Q000166:cytology* / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D013997:Time Factors