Change in T-Lymphocyte Count after Initiation of Highly Active Antiretroviral Therapy in HIV-Infected Patients with History of Mycobacterium Avium Complex Infection

Abstract

Objective

To compare changes in CD4⁺, CD8⁺ and total lymphocyte counts after initiation of highly active anti-retroviral therapy (HAART) between HIV-infected patients with and without a recent history of Mycobacterium avium complex (MAC) infection.

Method

Matched exposed-non-exposed retrospective cohort study.

Results

Fifty-one patients with a recent history of MAC infection (MAC+) started a combination of at least three antiretroviral drugs. They were individually matched to 145 patients without any history of MAC infection (MAC-) according to CD4⁺ T-cell count (±30 cells/mm³), previous experience of antiretroviral treatment, AIDS clinical stage at the time of HAART initiation (baseline), age (±10 years) and gender. MAC+ and MAC- patients presented comparable median levels of total lymphocytes (488 vs 688/mm³, P=0.09), CD4⁺ (11 vs 16/mm³, P=0.15), CD8⁺ count (359 vs 386/mm³, P=0.39) and plasma HIV RNA (5.3 vs 5.1 log₁₀ copies/ml, P=0.22) at baseline. After 6 months on HAART, the median increase of CD4⁺ T-cell count was 28 cells/mm³ (interquartile range [IQR]: 1–63) in MAC+ and 72 cells/mm³ (IQR: 34–120) in MAC- patients (P<0.0001), whereas the percentage of CD4⁺ T cells was not significantly different between the two groups (P=0.13). Comparable differences were observed for total lymphocytes and CD8⁺ T cells (P<0.001). The 6 months decline of plasma HIV RNA was not significantly different according to MAC exposure (-1.6 in MAC+ vs -1.8 log₁₀ copies/ml in MAC- patients, P=0.65). Results were confirmed after adjustment for other characteristics than the matching variables and after taking into account potential informative bias due to unbalanced number of deaths between the two groups.

Conclusion

MAC infection at the time of HAART initiation is an important deleterious factor for immune reconstitution. A better understanding of the underlying mechanism and an evaluation of additional treatment strategies are necessary to help immune restoration in such circumstances.