Survival, GVHD, and cytokines. (A-B) Survival (A) and GVHD scoring (B) after experimental allogeneic bone marrow transplantation. Animals received transplants after 2 × 600 cGy total body irradiation and were scored for GVHD as described.^1,2  Animals received autoclaved water containing probiotic lactobacteria (L rhamnosus GG) or autoclaved water alone. Animals receiving probiotics displayed reduced mortality during the early phase after transplantation and thereafter (12 to 14 animals per group, P < .01). At the same time, GVHD was significantly reduced in animals receiving L rhamnosus GG after transplantation (^*P < .02, control versus L rhamnosus GG). (C) Total numbers of CD3⁺ spleen cells were also significantly reduced in mice receiving L rhamnosus GG (^*P < .02 compared with control treated mice, Mann-Whitney test). (D) Cytokine release by splenic cells at day 13 after allogeneic bone marrow transplantation. Cells from 4 individual mice were plated at 200 000 cells per well. Some cells were stimulated with 100 ng LPS per milliliter. Culture supernatants were harvested after 24 hours of culture and immediately analyzed for cytokines. Upon LPS stimulation, splenic cells from animals treated with L rhamnosus GG displayed a lower release of IFN-γ (^*P = .02, control plus LPS versus L rhamnosus GG plus LPS, and antibiotics plus LPS versus control plus LPS).