Leukocytes expressing green fluorescent protein as novel reagents for adoptive cell transfer and bone marrow transplantation studies

Transgenic mice expressing green fluorescent protein (GFP) were generated t o provide a source of labeled leukocytes for cell transfer studies. The tra nsgene comprises the GFP coding region under the transcriptional control of the chicken beta -actin promoter and human cytomegalovirus enhancer. Mice expressing this GFP transgene were generated in the B6D2 and in the 129SvEv backgrounds. Flow cytometric analysis of cells from the Mood, spleen, and bone marrow of these transgenic mice revealed that most leukocytes, includi ng dendritic cells and memory T cells, express GFP. In allogeneic cell tran sfers, donor GFP+ splenocytes were detected in the spleen and mesenteric ly mph nodes of recipient mice within 2 hours after transfer and for at least 9 days thereafter. In syngeneic experiments using 129-derived GFP+ donor sp lenocytes, donor cells were detected in multiple tissues of 129 recipients from 2 hours to 3 weeks after transfer. In bone-marrow transplantation expe riments using irradiated allogeneic recipients, the percent of GFP+ donor c ells in recipients at 3 weeks was comparable to that seen in similar tissue s of GFP+ donor mice. These data demonstrate that GFP+ transgenic mice prov ide a ready source of GFP-expressing primary cells that can be easily monit ored after their transfer to recipient animals.