RECOMBINANT HUMAN IL-7 ADMINISTRATION IN MICE AFFECTS COLONY-FORMING UNITS-SPLEEN AND LYMPHOID PRECURSOR CELL LOCALIZATION AND ACCELERATES ENGRAFTMENT OF BONE-MARROW TRANSPLANTS

Murine reconstitution assays were used to investigate the effects of r ecombinant human interleukin-7 (rhIL-7) on myeloid and lymphoid precur sors and on bone marrow engraftment, Reconstitution with bone marrow f rom rhIL-7-treated mice results in a 3.4-fold decrease in total colony -forming unit-spleen (CFU-S) activity (day 9) and an 18.1- and 11.9-fo ld decrease in its ability to generate thymocytes and splenic B lineag e cells, respectively, In contrast, after reconstitution with splenocy tes from rhIL-7-treated mice, CFU-S activity increased 23.6-fold (day 9) and the thymocyte and splenic B lineage cell regenerative capacity increased by 4.0- and 3.2-fold, respectively, In addition, CD43(low+), B220(low+) cells that contain pre-pro-B cells and pro-B cells were ex panded two- to threefold and Ig mu(-), B220(+), CD2(-) and Ig mu(-), B 220(+), CD2(+) B lineage cells were expanded approximately 10-fold and 10- to 45-fold (depending on the tissue examined), respectively, afte r rhIL-7 treatment, Administration of rhIL-7 to irradiated mice transp lanted with bone marrow resulted in accelerated T cell and B cell reco nstitution by up to 2-4 weeks, Thus, rhIL-7 administration affects the distribution of myeloid and lymphoid precursors, Moreover, rhIL-7 adm inistration accelerates murine bone marrow cell engraftment and theref ore may be useful in reducing the engraftment time in bone marrow tran splant patients.