Do nucleoside analogues directly influence T-lymphocyte subset counts? The pediatric model

Impact of sub-optimal HIV viral control on activated T cells

OBJECTIVE

HIV viral load (VL) monitoring is generally conducted 6-12 monthly in low- and middle-income countries, risking relatively prolonged periods of poor viral control. We explored the effects of different levels of loss of viral control on immune reconstitution and activation.

DESIGN

Two hundred and eight participants starting protease inhibitor (PI)-based second-line therapy in the EARNEST trial (ISRCTN37737787) in Uganda and Zimbabwe were enrolled and CD38 + /HLA-DR + immunophenotyping performed (CD8-FITC/CD38-PE/CD3-PerCP/HLA-DR-APC; centrally gated) in real-time at 0, 12, 48, 96 and 144 weeks from randomization.

METHODS

VL was assayed retrospectively on samples collected every 12-16 weeks and classified as continuous suppression (<40 copies/ml throughout); suppression with transient blips; low-level rebound (two or more consecutive VL >40, <5000 copies/ml); high-level rebound/nonresponse (two or more consecutive VL >5000 copies/ml).

RESULTS

Immunophenotype reconstitution varied between that defined by numbers of cells and that defined by cell percentages. Furthermore, VL dynamics were associated with substantial differences in expression of CD4 + and CD8 + cell activation markers, with only individuals with high-level rebound/nonresponse (>5000 copies/ml) experiencing significantly greater activation and impaired reconstitution. There was little difference between participants who suppressed consistently and who exhibited transient blips or even low-level rebound by 144 weeks ( P  > 0.2 vs. suppressed consistently).

CONCLUSION

Detectable viral load below the threshold at which WHO guidelines recommend that treatment can be maintained without switching (1000 copies/ml) appear to have at most, small effects on reconstitution and activation, for patients taking a PI-based second-line regimen.

Metabolic and Immunological Effects of Antiretroviral Agents in Healthy Individuals Receiving Post-Exposure Prophylaxis

We have assessed metabolic and immunological effects of a nelfinavir-containing regimen in healthy HIV-1-uninfected individuals receiving post-exposure prophylaxis. Our data suggest that this regimen is well tolerated and did not modify the lipid or hepatic profiles. This antiretroviral regimen seems to have no effect on lymphocyte T cell subsets, however, it could have an immune-modulator role, inducing an increase in the proliferative responses to mitogens.

Safety of late in utero exposure to zidovudine in infants born to human immunodeficiency virus-infected mothers: Bangkok. Bangkok Collaborative Perinatal HIV Transmission Study Group

BACKGROUND

Short-course zidovudine (ZDV) given in the late antenatal period can reduce mother-infant human immunodeficiency virus (HIV) transmission by one half. Because this intervention is being implemented in developing countries, evidence of its safety is needed.

METHODS

In a randomized, double-blinded, placebo-controlled trial in Bangkok, HIV-infected pregnant women received either ZDV (300 mg twice daily from 36 weeks' gestation until labor, then every 3 hours until delivery) or an identical placebo regimen. Infants were evaluated at birth and at 1, 2, 4, 6, 9, 12, 15, and 18 months of age. Growth, clinical events, and hematologic and immunologic measurements were compared between treatment groups.

RESULTS

Of the 395 children born (196 in ZDV group and 199 in placebo group), 330 were uninfected, 55 were infected, and 10 had indeterminate infection status. Overall, 319 children (81%) completed 18 months of follow-up, and 14 (4%) died before 18 months of age. Among uninfected children, the mean hematocrit was lower in the ZDV group at birth (49.1% vs 51.5%) but not at later ages; mean weight, height, head circumference, and CD4(+) and CD8(+) T lymphocyte counts were similar in both groups at all ages. Five uninfected children in the ZDV group but only one in the placebo group had a febrile convulsion. No other signs suggestive of mitochondrial dysfunction and no tumors were observed. Among infected children, an estimated 62% in the ZDV group and 77% in the placebo group survived free of Centers for Disease Control and Prevention class C disease during the 18-month follow-up.

CONCLUSIONS

No significant adverse events were associated with short-course ZDV during 18 months of follow-up in this population.

Brief report: effect of antiretroviral agents on T-lymphocyte subset counts in healthy HIV-negative individuals. The Italian Registry on Antiretroviral Postexposure Prophylaxis

To study the effect of antiretroviral agents on T-lymphocyte counts in HIV-negative individuals, total counts and CD4+ and CD8+ lymphocyte counts were measured in health care workers (HCW) who had been occupationally exposed to HIV who were untreated (164 HCW, group A), or had received antiretroviral postexposure prophylaxis (PEP). PEP included zidovudine (150 HCW, group B), zidovudine plus lamivudine (48 HCW, group C), or zidovudine, lamivudine, and indinavir (85 HCW, group D), at standard dosage for a mean of 30, 27, and 27 days of treatment, respectively. Lymphocyte values were collected after a mean of 44 days following exposure in group A, 48 days in group B, and 30 days both in groups C and D. Student's t-, nonparametric Mann-Whitney, and Kruskal-Wallis tests were used for statistical analysis. A slight increase in mean CD4 (range, 4.8%-6. 7%) and CD8 (range, 1.4%-9.3%) cells/mm3 was observed in each group. Gender, PEP duration, side effects, and follow-up time did not correlate with responses. Data did not vary using CD4 and CD8 percentages. These findings seem to reject any direct effects of antiretroviral agents, independent of retroviral inhibition, on proliferation and redistribution of T lymphocytes, as well as the hypothesized braking of lymphocyte apoptosis. The observed variations could reflect biologic variability.