A study in the September 24 edition of the journal AIDS suggests that long-term antiretroviral therapy can lead to an increase in immune system activation and falling CD4-cell levels, particularly between four and six years of continuous treatment.
Follow-up of 20 adults on combination therapy for between 41/2 and 6.2 years'17 of whom were still on their initial regimen of AZT, 3TC, and Norvir'showed that 55% experienced CD4-cell drops between the fifth and sixth years of treatment. Activated CD4- and CD8-cell percentages also climbed between the third and sixth years of treatment, indicating elevated immune system activation. Researchers say falling CD4-cell levels and immune activation could be caused by low-level increases in viral replication occurring after lengthy anti-HIV treatment. Rising CD4 numbers during the first few years of therapy also could be providing new sources for viral infection and replication, they conlcude.
