Disrupted Homeostatic Cytokines Expression in Secondary Lymph Organs during HIV Infection

Research has firmly established that infection by human immunodeficiency virus (HIV) leads to structural disruption in secondary lymph organs (SLOs) and that IL-7 expression by SLOs is downregulated in simian immunodeficiency virus (SIV)-infected rhesus macaques. However, the foregoing has not been demonstrated in HIV-infected patients. As well, SLO-produced chemokines and cytokines, other than IL-7, have not been tested. In this study, SLOs in HIV-infected patients exhibit decreased levels of lymphoid cytokines, such as IL-7 and C-C motif chemokine ligand 21 (CCL21), due to lower expression of lymphotoxin (LT)-β. Previous research has shown that LT-β is produced mainly by CD4⁺T cells in rhesus macaques, while our study found the same level of LT-β expressed by CD4⁺T and CD8⁺T cells in humans. CD8⁺T cells substitute for depleted CD4⁺T cells LT-β production. Only the total number of CD3⁺T cells can account for the majority of LT-β in human SLOs. This study indicates a possible mechanism and a potential target for improvement of SLO function in HIV-infected patients, a novel adjuvant therapy for AIDS.