Increased polyclonal CD5+ B1a lymphocytes in a haploidentical stem cell transplant recipient.
BACKGROUND
Atypical lymphocyte populations may be seen in the peritransplant setting. In this case report, we describe an unusually high number of CD5+ B-cells (B1a cells) following transplant.


METHODS
B1a cells identified during routine follow-up by immunophenotypic analysis in a middle-aged man who had a haploidentical stem cell transplant for acute myeloid leukemia were compared with a reference set of post-transplant samples.


RESULTS
Increased but polyclonal B1a cells were identified with 100% donor chimerism.


CONCLUSIONS
Our case demonstrates that a high absolute number of B1a cells may be seen post-transplant and should not be confused with an atypical CD5+ lymphoproliferative disorder. Furthermore, the population of polyclonal CD5+ B lymphocytes from the patient's donor is prominent 7 months post-transplant. This suggests that the maintenance of CD5+ B1 cells prior to conversion to adult-type CD5⁻ B2 cells is not hindered by the recipient adult stromal environment.
Hillard
Robert A
RA
Department of Pathology and Laboratory Medicine, Chandler Medical Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA. rahill5@email.uky.edu
Lekakis
Lazaros J
LJ
Pulliam
Joseph F
JF
D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology*; D018956:CD5 Antigens / Q000276:immunology*; D002469:Cell Separation; D003001:Cloning, Molecular; D005434:Flow Cytometry; D005500:Follow-Up Studies; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000175:diagnosis / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome
D018956:CD5 Antigens