Influence of repeated cycles of structured therapy interruption on the rate of recovery of CD4+ T cells after highly active antiretroviral therapy resumption.

BACKGROUND

CD4+ T cell recovery dynamics were analysed during the 'on treatment' periods in structured therapy interruption (STI) as well as the long-term immune reconstitution with highly active antiretroviral therapy (HAART) after finishing STI.

METHODS

One hundred and twenty HIV-1-infected patients on successful HAART were randomized to receive for 2 years continuous HAART (n=37) or two different strategies of STI (n=83). After this period, most patients received continuous HAART for 2 years.

RESULTS

During the STI period, the rate of recovery of CD4+ T cells decreased progressively from the first to the last resumption of HAART {median change of increase: +232 [interquartile range (IQR): +126, +318], +116 (IQR: +10, +471), +87 (IQR: -54, +252) and -26 (IQR: -352, +211) cells/mm3 after the first, second, third and fourth resumption, respectively}. After the STI period and 2 years of continuous HAART, the median CD4+ count remained significantly lower than at baseline in STI arms, both in the virological arm [559 (IQR: 383, 727) versus 771 (IQR: 625, 913) cells/mm3, P<0.0001] and the immunological arm [619 (IQR: 501, 789) versus 787 (IQR: 657, 954) cells/mm3, P<0.0001], but not in the control arm [886 (IQR: 564, 1122) versus 780 (IQR: 539, 945) cells/mm3, P=0.68]. In a multivariate analysis, the nadir of CD4+ T cells and the baseline value of CD4+ before the STI period independently predicted the level of CD4+ T cells 2 years after resumption of HAART (in both cases, P<0.0001).

CONCLUSION

The drop in CD4+ cell count after a first and a second period of 3 months of interruption of HAART was completely recovered after resuming HAART; conversely, interruptions longer than 6 months were deleterious for the recovery of CD4+. CD4+ cell count did not rebound completely in patients who received 2 years of HAART after 2 years of STIs.