Interferon gamma and tumour necrosis factor alpha are overexpressed in bone marrow T lymphocytes from paediatric...

Twelve paediatric patients with aplastic anaemia and two groups of normal control subjects underwent flow cytometric analysis for intracytoplasmic expression of gamma interferon (gamma-IFN) and tumour necrosis factor alpha (TNF-alpha) in bone marrow and peripheral blood CD4+ and CD8+ cells. The same cytokines were tested, by immunoassay, in culture supernatants from unstimulated bone marrow mononuclear cells (MNCs). Marrow CD4+ and CD8+ cells expressing gamma-IFN and TNF-alpha were significantly increased in the patients in comparison with normal control subjects (P from < 0.05 to < 0.0001 in the different cellular subsets). Patients' marrow CD4+ and CD8+ cells containing gamma-IFN and TNF-alpha were significantly increased when compared with the same cell fractions from paired peripheral blood samples (P from < 0.05 to < 0.0001 in the various cellular subsets). In the supernatant of marrow MNCs, gamma-IFN and TNF-alpha were detected in four out of eight and five out of eight cases, respectively, whereas neither cytokine was traceable in the control subjects. Patients' peripheral blood CD4+ and CD8+ cells containing gamma-IFN and TNF-alpha were not significantly increased in comparison with those from normal control subjects. Whereas patients with favourable and unfavourable outcomes had no significantly different proportions of marrow gamma-IFN+/CD4+ and gamma-IFN+/CD8+ cells, the percentages of marrow CD4+ and CD8+ cells containing TNF-alpha were significantly lower in subjects with favourable than in those with unfavourable outcome. Overall, these findings show that, in aplastic patients, T cells overexpressing gamma-IFN and TNF-alpha concentrate in the bone marrow and that intracytoplasmic expression of TNF-alpha in marrow CD4+ and CD8+ cells is associated with an unfavourable clinical course.