Morphofunctional evolution of thymus response after first-line combined antiretroviral therapy in adult HIV-infected patients

Abstract

Objective and methods. – Ten consecutive HIV infected patients were evaluated to assess the relationship among thymic residual tissue, first-line antiretroviral therapy, thymic size evolution, and markers of HIV disease progression. Computerized tomography (CT) study of thymus was performed before starting a triple antiretroviral therapy, and repeated after 12 months, and thymic size was evaluated by a standard score staging. Results. – Initial thymic size tested significantly dependent on patients’ age, while no other variable seemed to affect this feature, but baseline CD4+ lymphocyte count. After a 12-month therapy, a relationship between increased thymus score, and a favourable therapeutic response proved evident. Increase (three cases) or maintenance (four cases) of thymic volume paralleling the treatment-related immune system recovery obtained after 12 months of HAART, may represent the morphological response to an effective therapy. Patients with increase of thymic size experienced a greater 12-month rise of mean CD4+ lymphocyte count compared with baseline levels, opposed to patients maintaining their baseline thymic index. The temporal evolution of both absolute CD8+ cell count and plasma HIV-RNA levels, did not reveal any significant difference compared with baseline levels (patients maintaining a stable thymus volume versus those experiencing an increase of thymus CT score) although a tendency towards a better gain of CD4+ cell count and drop of viremia tested more evident among the patients with an increased thymus score. Conclusion. – Thymopoiesis has a key role in the immune recovery following antiretroviral therapy in adults, and a relationship between morphological and functional activity of thymus is confirmed.