Expression of functional B7-H2 and B7.2 costimulatory molecules and their prognostic implications in de novo acute myeloid leukemia.
OBJECTIVE
The B7 family molecules have been shown to regulate immune responses in both positive and negative fashions. Their roles in the progression of human cancers, however, are not well established. The aim of this study was to examine whether leukemic cells of acute myeloid leukemia express functional B7 family molecules and, if so, whether such expression has any clinical significance.


METHODS
The expression of four B7 family molecules, B7.1, B7.2, B7-H1, and B7-H2, on leukemic cells from acute myeloid leukemia patients was analyzed by flow cytometry. The function of the expressed molecules was examined by the allogeneic mixed lymphocyte-leukemic cell reaction, and their relationship to the clinical data and survival was analyzed.


RESULTS
Although B7.1 and B7-H1 expressions were rare, the cells from a substantial number of acute myeloid leukemia cases expressed B7.2 and B7-H2 molecules [mean percentages of B7.2- and B7-H2-positive cells were 28.9% (n = 58) and 15.3% (n = 59), respectively]. Patients in whom >25% of leukemic cells expressed B7-H2 had significantly shorter survival, and this B7-H2 positivity had the strongest prognostic value when B7-H2 and other prognostic factors were analyzed together by multivariate analysis (P = 0.0108). Furthermore, B7.2 expression was associated with hyperleukocytosis (P = 0.026). Consistent with this finding, acute myeloid leukemia cells expressing B7.2 and B7-H2 induced allogeneic CD4+ T cells to proliferate and secrete interleukin-4 and interleukin-10 in vitro, effects that were partially blocked by antibodies against B7.2 and B7-H2.


CONCLUSIONS
Our results indicate the expression of functional B7.2 and B7-H2 molecules, and these molecules may facilitate progression of acute myeloid leukemia.
Tamura
Hideto
H
Third Department of Internal Medicine, Nippon Medical School, Tokyo, Japan. tam@nms.ac.jp
Dan
Kazuo
K
Tamada
Koji
K
Nakamura
Kyoko
K
Shioi
Yumiko
Y
Hyodo
Hideya
H
Wang
Sheng-Dian
SD
Dong
Haidong
H
Chen
Lieping
L
Ogata
Kiyoyuki
K
D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D015703:Antigens, CD; D051940:B7-2 Antigen / Q000032:analysis / Q000235:genetics*; D001854:Bone Marrow Cells / Q000378:metabolism / Q000473:pathology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000737:chemistry / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic; D018922:HL-60 Cells; D006801:Humans; D060945:Inducible T-Cell Co-Stimulator Ligand; D007371:Interferon-gamma / Q000378:metabolism; D016753:Interleukin-10 / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism; D015847:Interleukin-4 / Q000378:metabolism; D019169:Jurkat Cells; D020014:K562 Cells; D007951:Leukemia, Myeloid / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011506:Proteins / Q000032:analysis / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016019:Survival Analysis; D020298:U937 Cells
D015703:Antigens, CD; D051940:B7-2 Antigen; C497964:CD86 protein, human; D017077:Culture Media, Conditioned; C498514:ICOSLG protein, human; D060945:Inducible T-Cell Co-Stimulator Ligand; D007376:Interleukin-2; D011506:Proteins; D012333:RNA, Messenger; D016753:Interleukin-10; D015847:Interleukin-4; D007371:Interferon-gamma