Dear Omer,

Good day, a decent article by Heylmann D et al from Mainz, Germany showed that immune suppressive regulatory T cells (Treg) are particularly hypersensitive to low dose cyclophosphamide, hence, while being inhibited will cause immune stimulation. Whereas high-dose cyclophosphamide will exhibit cytotoxic effect to ablate immune cells, as used for post-transplant GVHD prevention therapy.

Thank you very much Dr.Victor

I found the paper you talked about I think it is

http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0083384

Dear Omar,

Dimeloe S et al reported following paper. Hope it may help. 

Human regulatory T cells lack the cyclophosphamide-extruding transporter ABCB1 and are more susceptible to cyclophosphamide-induced apoptosis.

http://onlinelibrary.wiley.com/doi/10.1002/eji.201444879/epdf