CD4 T cells programmed to traffic to lymph nodes account for increases in numbers of CD4 T cells up to 1 year after the initiation of highly active antiretroviral therapy for

Cells programmed to traffic through lymph nodes dominate initial increases in total CD4(+) T cell numbers after highly active antiretroviral therapy (HAART) is begun for human immunodeficiency virus type 1 (HIV-1) infection. However, it is unknown whether this dominance continues throughout the first year of treatment. To examine this question, 10 subjects who had a positive response to HAART for 1 year were selected from a cohort of 20 who were receiving this treatment. Flow cytometry, which was used to characterize CD4(+) T cell subsets by immunophenotype, demonstrated that cells programmed to traffic through lymph nodes, irrespective of their memory or naive phenotype, continued to best account for increases in CD4(+) T cells, even 1 year after starting HAART. This suggests that, although this pool is preferentially depleted during HIV-1 infection, HAART allows for reaccumulation of these cells for at least 1 year. Furthermore, it suggests that phenotypic differences based on markers of lymphocyte trafficking may be more relevant for understanding HIV-1 pathogenesis than are naive and memory markers alone.