Figure 1. Depletion of CD4⁺ or CD8⁺ cells prevents rejection of a BALB.B BMT in BALB LR-PLT transfused recipients.

(A) Experimental model testing requirement of CD4⁺ and CD8⁺ depletion in platelet transfusion induced BMT rejection. While BALB/c donors were MHC- and mHA-mismatched, BALB.B BM donors were MHC-matched:mHA-mismatched to the recipients. Designated recipients received two platelet transfusions a week apart. After the second transfusion, indicated recipients were treated i.p. with anti-CD4 (clone: GK1.5) or anti-CD8β (clone: H35) depleting antibodies, or isotype control antibodies Rat IgG2_b or Rat IgG, respectively. Depletion of CD4⁺ or CD8⁺ T cells was monitored in the peripheral blood, spleen, peripheral lymph nodes, and BM. Twenty-four hours after the second treatment, designated recipients received a BALB.B BMT under reduced intensity conditions. Seroanalysis and in vivo survival of BALB.B targets was also performed after BMT (see figure 2). (B) Depletion analysis of CD4⁺ and CD8⁺ T cells in BMT recipients. Peripheral blood leukocytes from BMT recipients were stained for CD4⁺ or CD8⁺ T cells using anti-CD4 (clone: RM4-5) and anti-CD8α (clone: 53-6.7) antibodies. (C) BALB.B BMT engraftment results. Percent CD229.1⁺ cells in the peripheral blood represent engraftment; the mean of each group is represented as a horizontal line. Statistics were generated using column statistics and a one-way ANOVA with Dunnett’s post-test. Illustrated is the combined data from three independent experiments.