PTCy with BBG reduces serum human IFNγ concentrations compared to PTCy alone at endpoint. (a–h) Spleen suspensions from treated humanised mice at endpoint (Figure 1) were examined by flow cytometry to determine the proportions of (a) human (h) CD45+ leukocytes, (b) hCD3+ T cells, (c) hCD4+ or hCD8+ T cells, (e) hCD4+hCD25+hCD127lo regulatory T cell (hTreg), (f) hCD39+ Tregs, or (g) hCD19+ B cells. (d) The ratio of hCD4+ to hCD8+ T cells was calculated from (c). (h) Serum hIFNγ concentrations were examined by a flow cytometric LEGENDPlex kit. (a–h) Data are presented as mean ± SEM. Symbols represent individual mice (n = 10, PTCy + BBG; n = 11, PTCy).