The applicants have demonstrated an unusual association of apparently unrelated hematological abnormalities in a group of HIV-l infected individuals. HIV-l seropositive, thrombocytopenic individuals showed marked alterations in their B-cell subsets. Although B-cell numbers were normal, both the proportion of CD5+ cells and their absolute number were increased and the absolute number of CD5- B-cells were markedly reduced. In some patients 90 percent of the circulating B-cells were CD5+ (normal=18.2 + 2.3%). The alteration in the B-cell subsets was neither attributable to changes in CD4 or CD8 cell number, CD4/CD8 ratio, or absolute lymphocyte count nor to severity of disease nor to AZT treatment. The applicants suggest that it is improbable that the association of thrombocytopenia and aberrant B-cell profile occurred through happenstance. Their proposal is designed to investigate the basis of the association. Three possible explanations will be examined: (1) Both the abnormalities could be consequences of an autoimmune response, associated with the prevalence of CD5+ B cells, and directed against either the mature cells or their progenitors in the marrow. Sera from infected patients will be assayed for autoantibodies reactive with B cells and platelets or their progenitors. The applicants will also seek cell-bound autoantibodies or immune complexes similar to those found on platelets of patients with HIV-1 + ITP. If anti-B-cell antibodies are found, they will determine how CD5+ B-cells escape this autoimmune response. (2) The abnormalities could be a direct effect of HIV-l infection on either a hematopoietic precursor or a cell necessary for the development of B-cells and megakaryocytes. Both long term bone marrow cell cultures and short-term clonal cultures will be used to study the effects of virus, HIV-l infected cells and serum on the development of B-cells. (3) The changes in lympho-hematopoiesis could be a result of dysregulation induced by either the deficiency of CD4+ T- cells or the excess of CD8+ T-cells. T-cell derived cytokines are known to have profound effects on both MK and B-cell development. The relative T-independence of the CD5+ subset may account for their persistence. This possibility will be examined using two model systems. In the first, selected populations of human cells from uninfected subjects will be transferred to immunodeficient (SCID) mice. Cell sorting will be used to isolate highly enriched populations of CD5+ and CD5- B-cells, or their precursors as well as T-cell populations expressing either CD4 or CD8. Various combinations of these populations will be injected and the survival of the B-cell subsets determined. In the second model, an attempt will be made to reproduce the phenomenon in a totally murine system. Again, cells of the necessary phenotypes will be prepared by cell sorting and injected into SCID mice, but in this model only cells from syngeneic mice will be transferred, eliminating the possibility that problems of histo-incompatibility will confound the developmental studies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK049895-02
Application #
2150854
Study Section
Special Emphasis Panel (ZHL1-CSR-C (S1))
Project Start
1994-09-30
Project End
1998-08-31
Budget Start
1995-09-01
Budget End
1996-08-31
Support Year
2
Fiscal Year
1995
Total Cost
Indirect Cost
Name
New York University
Department
Pathology
Type
Schools of Medicine
DUNS #
004514360
City
New York
State
NY
Country
United States
Zip Code
10012
Dormady, S P; Bashayan, O; Dougherty, R et al. (2001) Immortalized multipotential mesenchymal cells and the hematopoietic microenvironment. J Hematother Stem Cell Res 10:125-40
Zhang, X; Dormady, S P; Basch, R S (2000) Identification of four human cDNAs that are differentially expressed by early hematopoietic progenitors. Exp Hematol 28:1286-96
Dormady, S P; Zhang, X M; Basch, R S (2000) Hematopoietic progenitor cells grow on 3T3 fibroblast monolayers that overexpress growth arrest-specific gene-6 (GAS6). Proc Natl Acad Sci U S A 97:12260-5
Basch, R S; Zhang, X M; Dolzhanskiy, A et al. (1999) Expression of CD41 and c-mpl does not indicate commitment to the megakaryocyte lineage during haemopoietic development. Br J Haematol 105:1044-54
Dolzhanskiy, A; Hirst, J; Basch, R S et al. (1998) Complementary and antagonistic effects of IL-3 in the early development of human megakaryocytes in culture. Br J Haematol 100:415-26
Steger, R W; Chandrashekar, V; Zhao, W et al. (1998) Neuroendocrine and reproductive functions in male mice with targeted disruption of the prolactin gene. Endocrinology 139:3691-5
Dolzhanskiy, A; Basch, R S; Karpatkin, S (1997) The development of human megakaryocytes: III. Development of mature megakaryocytes from highly purified committed progenitors in synthetic culture media and inhibition of thrombopoietin-induced polyploidization by interleukin-3. Blood 89:426-34
Basch, R S; Quito, F L; Beh, J et al. (1997) Growth of human hematopoietic cells in immunodeficient mice conditioned with cyclophosphamide and busulfan. Stem Cells 15:314-23
Basch, R S; Dolzhanskiy, A; Zhang, X M et al. (1996) The development of human megakaryocytes. II. CD4 expression occurs during haemopoietic differentiation and is an early step in megakaryocyte maturation. Br J Haematol 94:433-42
Dolzhanskiy, A; Basch, R S; Karpatkin, S (1996) Development of human megakaryocytes: I. Hematopoietic progenitors (CD34+ bone marrow cells) are enriched with megakaryocytes expressing CD4. Blood 87:1353-60

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