Adenosine deaminase (ADA) deficiency was discovered as a cause of severe combined immuno- deficiency twenty-five years ago and the genetic mechanisms responsible for the disease are well delineated. However, according to the investigator, the mechanism by which the loss of this enzyme causes immunodeficiency, and the relative contributions of the two ADA substrates, adenosine and deoxyadenosine, are still not understood. The investigator proposes to use murine fetal thymic organ culture (FTOC) with either ADA-/-mice or with normal mice and the ADA inhibitor 2'deoxycoformycin to elucidate the molecular mechanism for the failure of T-cell development in ADA deficiency. In this model the thymus is studied in isolation from all other organ systems allowing ADA deficient conditions to be maintained and at the same time eliminating the potential for glucocorticoid-mediated effects secondary to stress caused by multi-system disease. The investigator will first elucidate the stage where T-cell development is blocked (in the thymus) in the absence of ADA (Aim 1). Next, she will examine four potential mechanisms: dATP mediated inhibition of ribonucleotide reductase, suicide inactivation of S-adenosylhomocysteine hydrolase, aberrant adenosine receptor signaling and dATP induced DNA strand breaks (Aim 2). She will also characterize the defects in B-cell differentiation under ADA-deficient conditions using the placentally rescued ADA- knockout mice both in vivo and in a variety of in vitro culture systems (Aim 3). She will apply what she has learned about murine T-cell developments with ADA knock-out mice to human thymocyte differentiation by characterizing residual T- cells in ADA-deficient patients and performing chimeric human/mouse fetal thymic organ cultures (Aim 4). The experiments proposed above will not only give new insight into the pathogenesis of the severe combined immunodeficiency seen in ADA deficiency, but will also yield new knowledge about the regulation of normal lymphocyte development.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD036044-05
Application #
6521049
Study Section
Immunological Sciences Study Section (IMS)
Program Officer
Lock, Allan
Project Start
1998-09-01
Project End
2003-12-14
Budget Start
2002-06-01
Budget End
2003-12-14
Support Year
5
Fiscal Year
2002
Total Cost
$212,758
Indirect Cost
Name
Oklahoma Medical Research Foundation
Department
Type
DUNS #
937727907
City
Oklahoma City
State
OK
Country
United States
Zip Code
73104
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Joachims, Michelle L; Marble, Patrick; Knott-Craig, Christopher et al. (2008) Inhibition of deoxynucleoside kinases in human thymocytes prevents dATP accumulation and induction of apoptosis. Nucleosides Nucleotides Nucleic Acids 27:816-20
Joachims, Michelle L; Chain, Jennifer L; Hooker, Scott W et al. (2006) Human alpha beta and gamma delta thymocyte development: TCR gene rearrangements, intracellular TCR beta expression, and gamma delta developmental potential--differences between men and mice. J Immunol 176:1543-52
Van De Wiele, C Justin; Joachims, Michelle L; Fesler, Amy M et al. (2006) Further differentiation of murine double-positive thymocytes is inhibited in adenosine deaminase-deficient murine fetal thymic organ culture. J Immunol 176:5925-33
Eltzschig, Holger K; Faigle, Marion; Knapp, Simone et al. (2006) Endothelial catabolism of extracellular adenosine during hypoxia: the role of surface adenosine deaminase and CD26. Blood 108:1602-10
Chain, J L; Joachims, M L; Hooker, S W et al. (2005) Real-time PCR method for the quantitative analysis of human T-cell receptor gamma and beta gene rearrangements. J Immunol Methods 300:12-23
Thompson, Linda F; Vaughn, James G; Laurent, Aletha B et al. (2003) Mechanisms of apoptosis in developing thymocytes as revealed by adenosine deaminase-deficient fetal thymic organ cultures. Biochem Pharmacol 66:1595-9
Van De Wiele, C Justin; Vaughn, James G; Blackburn, Michael R et al. (2002) Adenosine kinase inhibition promotes survival of fetal adenosine deaminase-deficient thymocytes by blocking dATP accumulation. J Clin Invest 110:395-402
Thompson, L F; Van de Wiele, C J; Laurent, A B et al. (2000) Metabolites from apoptotic thymocytes inhibit thymopoiesis in adenosine deaminase-deficient fetal thymic organ cultures. J Clin Invest 106:1149-57