Metabolites from apoptotic thymocytes inhibit thymopoiesis in adenosine deaminase-deficient fetal thymic organ cultures.
Murine fetal thymic organ culture was used to investigate the mechanism by which adenosine deaminase (ADA) deficiency causes T-cell immunodeficiency. C57BL/6 fetal thymuses treated with the specific ADA inhibitor 2'-deoxycoformycin exhibited features of the human disease, including accumulation of dATP and inhibition of S-adenosylhomocysteine hydrolase enzyme activity. Although T-cell receptor (TCR) Vbeta gene rearrangements and pre-TCR-alpha expression were normal in ADA-deficient cultures, the production of alphabeta TCR(+) thymocytes was inhibited by 95%, and differentiation was blocked beginning at the time of beta selection. In contrast, the production of gammadelta TCR(+) thymocytes was unaffected. Similar results were obtained using fetal thymuses from ADA gene-targeted mice. Differentiation and proliferation were preserved by the introduction of a bcl-2 transgene or disruption of the gene encoding apoptotic protease activating factor-1. The pan-caspase inhibitor carbobenzoxy-Val-Ala-Asp-fluoromethyl ketone also significantly lessened the effects of ADA deficiency and prevented the accumulation of dATP. Thus, ADA substrates accumulate and disrupt thymocyte development in ADA deficiency. These substrates derive from thymocytes that undergo apoptosis as a consequence of failing to pass developmental checkpoints, such as beta selection.
Thompson
L F
LF
Immunobiology and Cancer Program, Oklahoma Medical Research Foundation, University of Oklahoma, Oklahoma City, 73104, USA. Linda-Thompson@omrf.ouhsc.edu
Van de Wiele
C J
CJ
Laurent
A B
AB
Hooker
S W
SW
Vaughn
J G
JG
Jiang
H
H
Khare
K
K
Kellems
R E
RE
Blackburn
M R
MR
Hershfield
M S
MS
Resta
R
R
D000243:Adenosine Deaminase / Q000172:deficiency* / Q000235:genetics; D000818:Animals; D017209:Apoptosis; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D005333:Fetus / Q000166:cytology / Q000378:metabolism; D006410:Hematopoiesis; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009924:Organ Culture Techniques; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics / Q000378:metabolism; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology / Q000378:metabolism
D017931:DNA Primers; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D000243:Adenosine Deaminase