Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired blood disease characterized clinically by chronic hemolysis causing hemoglobinuria, bone marrow failure (BMF), and a tendency to thrombosis. PNH is characterized by clonal proliferation of a hematopoietic cell with a somatic mutation in the X-linked PIG-A gene, as a result of which glycosylphosphadityilnositol (GPI)-linked proteins are deficient on the cell surface (since one of these is the complement- protective protein CD59, this explains the hemolytic and possibly the thrombotic manifestations). In the course of the previous grant period we have determined, based on an extensive analysis of mouse models of PNH and of normal human subjects, that PIG-A mutations are necessary but not sufficient for the development of PNH. In this renewal proposal we intend to test the specific hypothesis that, once a PIG-A mutation has taken place, it does not by itself confer a growth advantage to the mutant cell; rather, expansion of the mutant clone will take place only when it gams a conditional growth advantage by virtue of a special bone marrow environment. We further hypothesize that the selective mechanism depends on the presence in PNH patients of auto reactive lymphocytes that are able to attack and damage normal hematopoietic stem cells, but not PNH stem cells. Therefore, the specific aims of this proposal are as follows. (1) To identify auto-reactive lymphocytes in patients with PNH. We plan first to establish whether these are NK cells or T cells, and then to characterize them in terms of surface markers, TCR structure and functional properties. Preliminary data suggest we are dealing with CD3+CD8+ lymphocytes. (2) To identify the target of these auto-reactive lymphocytes. The most important inferred characteristic of these cells is that they must be able to discriminate between normal and PNH hematopoietic cells. This could mean that they recognize one of the numerous GPI-linked proteins expressed on hematopoietic stem cells; or that their reactivity depends on an accessory GPI-linked protein; or that the GPI glycophospholipid anchor is it the target. These possible alternatives will be tested in turn systematically; and we have already preliminary data which tend to favor the third possibility. (3)To isolate physically these lymphocytes from PNH patients, with the ultimate purpose to develop strategies for their specific ablation. For this purpose we intend to use CD1d refolding and tetramer technology. Isolation and quantitation of the specific T cell population we are postulating would provide a new tool in the diagnosis, prognosis and follow up of patients with FNH; in addition, since we suspect that we are dealing with a small subset of very powerful auto reactive cells, it is conceivable that we may find ways to ablate them specifically, rather than using drastic immuno suppression. The significance of this work might extend to clonal disorders other than PNH.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL056778-08
Application #
6619389
Study Section
Hematology Subcommittee 2 (HEM)
Program Officer
Qasba, Pankaj
Project Start
1996-08-01
Project End
2005-07-31
Budget Start
2003-08-01
Budget End
2005-07-31
Support Year
8
Fiscal Year
2003
Total Cost
$374,625
Indirect Cost
Name
Sloan-Kettering Institute for Cancer Research
Department
Type
DUNS #
064931884
City
New York
State
NY
Country
United States
Zip Code
10065
Araten, David J; Luzzatto, Lucio (2006) The mutation rate in PIG-A is normal in patients with paroxysmal nocturnal hemoglobinuria (PNH). Blood 108:734-6
Ellis, Nathan A; Kirchhoff, Tomas; Mitra, Nandita et al. (2006) Localization of breast cancer susceptibility loci by genome-wide SNP linkage disequilibrium mapping. Genet Epidemiol 30:48-61
Araten, David J; Thaler, Howard T; Luzzatto, Lucio (2005) High incidence of thrombosis in African-American and Latin-American patients with Paroxysmal Nocturnal Haemoglobinuria. Thromb Haemost 93:88-91
Araten, David J; Golde, David W; Zhang, Rong H et al. (2005) A quantitative measurement of the human somatic mutation rate. Cancer Res 65:8111-7
Mitra, Nandita; Ye, Tian-Zhang; Smith, Alex et al. (2004) Localization of cancer susceptibility genes by genome-wide single-nucleotide polymorphism linkage-disequilibrium mapping. Cancer Res 64:8116-25
Karadimitris, Anastasios; Araten, David J; Luzzatto, Lucio et al. (2003) Severe telomere shortening in patients with paroxysmal nocturnal hemoglobinuria affects both GPI- and GPI+ hematopoiesis. Blood 102:514-6
Bessler, Monica; Rosti, Vittorio; Peng, Yufeng et al. (2002) Glycosylphosphatidylinositol-linked proteins are required for maintenance of a normal peripheral lymphoid compartment but not for lymphocyte development. Eur J Immunol 32:2607-16
Araten, D J; Bessler, M; McKenzie, S et al. (2002) Dynamics of hematopoiesis in paroxysmal nocturnal hemoglobinuria (PNH): no evidence for intrinsic growth advantage of PNH clones. Leukemia 16:2243-8
Karadimitris, A; Li, K; Notaro, R et al. (2001) Association of clonal T-cell large granular lymphocyte disease and paroxysmal nocturnal haemoglobinuria (PNH): further evidence for a pathogenetic link between T cells, aplastic anaemia and PNH. Br J Haematol 115:1010-4
Araten, D J; Swirsky, D; Karadimitris, A et al. (2001) Cytogenetic and morphological abnormalities in paroxysmal nocturnal haemoglobinuria. Br J Haematol 115:360-8

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