Elevated vitamin B₁₂ levels in autoimmune lymphoproliferative syndrome attributable to elevated haptocorrin in lymphocytes.
OBJECTIVE
Identify the etiology of elevated B(12) in autoimmune lymphoproliferative syndrome (ALPS).


METHODS
Peripheral blood of ALPS patients with elevated B(12) and controls were evaluated.


RESULTS
Total and holo-haptocorrin (HC) levels were 26- and 23-fold higher in ALPS patients, respectively. No abnormal B(12)-binding proteins were found. Western blot revealed HC in lymphocyte lysates only from ALPS patients.


CONCLUSIONS
Elevated concentrations of B(12) found in ALPS patients were due to increased lymphocyte expression of HC.
Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA. rbowen@stanfordmed.org
Raffick A R
RA
Bowen
Kennichi C
KC
Dowdell
Janet K
JK
Dale
Steven K
SK
Drake
Thomas A
TA
Fleisher
Glen L
GL
Hortin
Alan T
AT
Remaley
Ebba
E
Nexo
V Koneti
VK
Rao
D056735:Autoimmune Lymphoproliferative Syndrome / Q000097:blood* / Q000473:pathology; D016022:Case-Control Studies; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism*; D011485:Protein Binding; D014155:Transcobalamins / Q000378:metabolism*; D014805:Vitamin B 12 / Q000097:blood*
D014155:Transcobalamins; D014805:Vitamin B 12