BCR and B-cell chronic lymphocytic leukemia: Therefore, we performed IGHV characterization of sorted CLL cells on four randomly selected lines of serial transplants (1st, 3rd, and 7th transplantation from primary tumor D22, 1st, 5th, and 6th transplantation from primary tumor C25, 1st and 2nd transplantation from primary tumor E31 and 1st transplantation from primary tumor 347) isolated from spleens of visibly ill recipients and compared BCR usage with matched original primary tumors.