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Thymus volume correlates with the progression of vertical HIV infection
A Vigano'1, S Vella, N Principi
1Cattedra di Pediatria IV, Università di Milano, Ospedale Luigi Sacco, Milan, Italy.
Background:
The thymus is the organ responsible for the maturation and selection of T lymphocytes and is thus pivotal in allowing the development of a functional immune system. Because in HIV infection cell-mediated immune responses are severely impaired, we studied the role of thymus in the control of the progression of HIV infection to AIDS.
Methods:
Thymic volume was analysed by magnetic resonance imaging in 31 vertically HIV-infected children. Plasma HIV viral load and phenotypic and functional cellular immunity-defining parameters were examined in the same patients.
Results:
Thymic volume was not correlated with age or nutritional status; thymic volume was nevertheless correlated with CD4 T-lymphocyte counts and with the percentage and absolute number of CD45RA+CD62L+ (naive) T lymphocytes. In addition, the ability of peripheral blood mononuclear cells to proliferate upon tetanus stimulation was directly proportional to thymic volume. Finally, a negative correlation was detected between thymic volume and HIV viral load.
Conclusion:
Because low HIV plasma viraemia and preserved immune function are favourable prognostic indices in HIV disease, these data indicate that an immunological, thymic-dependent control of the progression of HIV infection might be possible, at least in vertically transmitted HIV infection.