CCR1 expression is increased in GVHD target organs and the spleen after allogeneic SCT. Lethally irradiated B6D2F1 mice received SC transplants from either syngeneic B6D2F1 (□) or allogeneic B6 donors (■) as described in “Materials and methods.” (A,B) RNA was isolated from the intestines and liver of SC transplant recipients on weeks 1, 4, and 6 and CCR1 expression was determined by the RPA. Shown is a representative gel from week 4 (A). L32 is a ribosomal protein used as an mRNA loading standard. A line has been inserted to indicate where the gel was cut. The gels came from the same experiment but the intermediate area was cut. CCR1 mRNA expression was significantly increased after allo-SCT at all time points when compared with syngeneic controls (B) (data not shown). *P < .04; **P < .08; ***P < .001. (C) Splenic CD4⁺ and CD8⁺ T-cell expression of CCR1 was analyzed on days 7 and 11 and was found to be increased after allo-SCT when compared with syngeneic and naive controls. Data are shown for naive, syngeneic, and allogeneic splenic T cells stained for CD4⁺ or CD8⁺ (PE) and CCR1⁺ (FITC) on day 7. Numbers in the upper right corner of each graph represent the percentage of events in the corresponding quadrants.