Marrow mast cell counts do not predict bone marrow graft rejection.

High bone marrow mast cell counts before and after marrow transplantation have been reported to predict graft rejection in aplastic anemia. We tested this association by studying marrow specimens from 73 consecutive patients allografted for severe aplastic anemia, 21 of whom rejected. Mast cell counts per unit area were performed on aspirate smears stained with Wright-Giemsa stain and on particle sections, clot sections, and biopsy specimens of marrow stained with toluidine blue. The ranges in both rejecting and nonrejecting patients with both methods were wide. Smear counts were more variable and correlated poorly with section counts (correlation coefficient: +0.003). We found no differences between rejecting and nonrejecting patients, either before or after grafting, with regard to mast cell counts in marrow. Also alterations in myeloid:erythroid ratios bore no detectable relationship to rejection.