HIV-induced decline in blood CD4/CD8 ratios: viral killing or altered lymphocyte trafficking?

During HIV infection, CD4(+)-cell numbers and CD4/CD8 ratios decline in the blood. This is usually attributed to direct viral killing or to other indirect mechanisms. However, current models generally assume that such changes in the blood are representative of changes in total CD4(+)-cell numbers throughout the body. This article discusses the importance of alterations in CD4(+)- and CD8(+)-cell migration in regulating blood lymphocyte levels and questions the extent of virus-mediated CD4(+)-cell destruction.