Effects of of didanosine-related depletion of mtDNA in human T lymphocytes.
The normal metabolism of mitochondria in T lymphocytes is unknown, as are the effects from nucleoside-analogue reverse-transcriptase inhibitors that impair mitochondrial polymerase- gamma . We isolated peripheral-blood CD4 and CD8 T lymphocytes from 6 healthy men and stimulated them with anti-CD3 and anti-CD28 antibodies, in the presence and in the absence of didanosine (ddI). In the absence of ddI, mitosis of T lymphocytes was paralleled by a transient up-regulation of both mtDNA and production of lactate. In CD4 lymphocytes, 10-day incubation with ddI at concentrations of 11.8 mu mol/L, 35.4 mu mol/L, 59.0 mu mol/L, and 118.0 mu mol/L induced (1) a concentration-dependent reduction of both mtDNA (to 73%, 29%, 24%, and 23%, respectively, of the levels in control samples) and subunit II of mtDNA-encoded cytochrome c oxidase (to 86%, 81%, 55%, and 31%, respectively, of the levels in control samples) and (2) a concentration-dependent increase in production of lactate (to 139%, 222%, 276%, and 312%, respectively, of the levels in control samples). Activation of lymphocytes (which was measured in terms of expression of CD25) was unaffected. Mitochondrial depolarization (assessed by staining with JC-1) was observed as early as day 7 of incubation. All changes were time dependent and also were observed in isolated CD8 lymphocytes. Electron microscopy revealed enlarged mitochondria with vacuoles, inclusions, and reduced electron density. ddI at a concentration of 11.8 mu mol/L induced changes that bordered statistical significance. After stimulation, there was a wide range in the change of mtDNA content in lymphocytes. Therefore, mtDNA measurements in blood are not necessarily a marker for the mitochondrial toxicity of ddI. Nevertheless, ddI does lead to depletion of mtDNA in lymphocytes and to functional impairment.
Setzer
B
B
Medizinische Universitätsklinik, Department of Rheumatology and Clinical Immunology, Freiburg, Germany.
Schlesier
M
M
Walker
Ulrich A
UA
D000328:Adult; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000009:adverse effects*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000187:drug effects* / Q000378:metabolism*; D016049:Didanosine / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D028361:Mitochondrial Diseases / Q000139:chemically induced; D018894:Reverse Transcriptase Inhibitors / Q000008:administration & dosage / Q000009:adverse effects*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism
D019380:Anti-HIV Agents; D004272:DNA, Mitochondrial; D018894:Reverse Transcriptase Inhibitors; D016049:Didanosine