Human plasma contains a soluble form of CD86 which is present at elevated levels in some leukaemia patients.
Cell surface expression of CD86 (mCD86) provides an important co-stimulatory signal which profoundly influences immune responses. In this report, we investigated the potential presence of a circulating soluble form of CD86 (sCD86) in normal individuals and patients with acute myeloid leukaemia (AML) or B cell chronic lymphocytic leukaemia (B-CLL). Circulating sCD86 was detected in the plasma of all normal individuals (1.04 +/- 0.33 ng/ml, n = 51) and patients analysed. Plasma collected from AML patients in remission (n = 6) contained only low levels of sCD86 but significantly elevated levels (> or =2.65 ng/ml, P < 0.0001) were detected in 10/24 AML patients analysed at the time of presentation or relapse. Significantly elevated levels of sCD86 were also detected in 2/17 B-CLL patients. There was no correlation between sCD86 levels and other clinical parameters. RT-PCR analysis demonstrated that normal monocytes and dendritic cells, as well as isolated AML (n = 2) and B-CLL (n = 4) cells, expressed an alternatively spliced transcript of CD86 which encoded a soluble form absent in normal T, B and NK cells. The finding that a proportion of leukaemia patients contain elevated levels of sCD86 and that at least some leukaemic cells express sCD86 transcript suggests a potential role for sCD86 in modulating mCD86 signalling during the malignant process.
Hock
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BD
Haematology Research Group, Christchurch Hospital, PO Box 4345, Christchurch, New Zealand.
Patton
W N
WN
Budhia
S
S
Mannari
D
D
Roberts
P
P
McKenzie
J L
JL
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017398:Alternative Splicing; D015703:Antigens, CD / Q000097:blood* / Q000235:genetics*; D051940:B7-2 Antigen; D016022:Case-Control Studies; D003713:Dendritic Cells / Q000378:metabolism; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards; D005260:Female; D006801:Humans; D007938:Leukemia / Q000097:blood* / Q000378:metabolism / Q000473:pathology; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000097:blood / Q000378:metabolism / Q000473:pathology; D007951:Leukemia, Myeloid / Q000097:blood / Q000378:metabolism / Q000473:pathology; D008297:Male; D008562:Membrane Glycoproteins / Q000097:blood* / Q000235:genetics*; D008875:Middle Aged; D009000:Monocytes / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D012995:Solubility; D015854:Up-Regulation
D015703:Antigens, CD; D051940:B7-2 Antigen; C497964:CD86 protein, human; D008562:Membrane Glycoproteins; D012333:RNA, Messenger