Contrariwise to B-2 cells, BCR engagement in B-1 cells results in low proliferation rate and increased apoptosis population, whereas overactivation may be associated with lymphoproliferative disorders.
Additionally, rearrangement of the breakpoint cluster region (bcr) was demonstrated in the pretransplant blast crisis sample, but not in the posttransplant lymphoproliferation samples, thus confirming that these lymphoproliferative disorders were distinct.