Highly active antiretroviral therapy (HAART) initiated in advanced HIV disease is associated with CD4 lymphocyte increases (200-300 cells/mm3 after 2-4 years), although longer-term cellular dynamics have not been studied. We observed a significant median CD4 lymphocyte increase of 126 cells/mm3 and 54 naive CD4 lymphocytes from year 3 to 6 of HAART among 20 individuals with pre-HAART CD4 cell counts of 100-300 cells/mm3. This cohort represents the longest prospective immunological follow-up of virologically suppressed patients on HAART.

Human CD4+ T cells express P-glycoprotein (P-gp), the ATP binding cassette efflux transporter encoded by MDR1. A common MDR1 single-nucleotide polymorphism in exon 26 (C3435T), which is linked to an exon 21 polymorphism (G2677T/A) and reportedly alters expression, has been associated with greater CD4+ T-cell increases during antiretroviral therapy. P-gp overexpression prevents apoptosis and inhibits HIV-1 replication in model systems, suggesting a potential effect on T-cell turnover. This study explored relationships between MDR1 polymorphisms and phase 1 viral decay among 31 HIV-infected individuals initiating antiretroviral therapy. Position 3435 genotypes were CC in 7 (23%), CT in 14 (45%), and TT in 10 (32%). Position 2677 genotypes were GG in 8 (26%), GT in 18 (58%), and TT in 5 (16%). There was no significant relationship between allelic variants in either exon 26 or 21 and phase 1 or phase 2 viral decay, changes in lymphocyte subsets over time, or plasma trough ritonavir concentrations. It is concluded with 95% confidence that phase 1 viral decay differences between exon 26 TT and CC groups are unlikely to exceed 18%.

We compared immune restoration in patients who suppressed human immunodeficiency virus type 1 replication after treatment with a protease inhibitor (PI) plus nevirapine or with 3 nucleoside reverse-transcriptase inhibitors (NRTIs) plus nevirapine. Changes in total and memory CD4 and CD8 cells were similar in the groups, as were decreases in immune activation (e.g., CD38 and HLA-DR) and increases in CD28 expression. Increases in naive CD4 and CD8 cells tended to be greater in the NRTI-treated group, with differences in naive CD4 cells significant at weeks 8 and 12 (P<.05) but not at week 48. Lymphocyte apoptosis decreased in both groups, but the week-1 decrease was greater in the PI-treated group (P<.02). Lymphocyte proliferation and skin-test responses were comparable. We find little evidence for differences in the major direct immunologic effect of PI versus NRTI regimens and propose that effects observed elsewhere were indirect, mediated through antiviral activity or adaptation of the virus to selection pressure.

Objective: To describe the magnitude of immune restoration after long-term control of HIV-1 replication.Design: Prospective study of immune restoration in patients starting highly active antiretroviral therapy (HAART).Methods: Patients with moderately advanced HIV-1 infection (CD4 cells between 100 x 10(6) and 300 x 10(6)/1) who enrolled in a trial of HAART and who had suppression of HIV-1 replication during 3 years of therapy were evaluated for phenotypic and functional indices of immune restoration.Results: Almost all immune restoration achieved occurred during the first year, The median CD4 lymphocyte count increased by 159 x 10(6) cells/l during the first year (P < 0.001); CD4 lymphocyte rises during the second and third years were not significant. Most decreases in activation antigen expression (CD38/HLA-DR) on CD4 and CD8 lymphocytes occurred during the first year, and after 3 years, patient lymphocytes were still abnormally activated. The proportion of CD4 lymphocytes expressing CD28 increased during the first and second years, but even after 3 years, CD28 expression on CD4 cells remained abnormally low, Lymphocyte proliferative responses to Candida normalized during the first 12 weeks of HAART while responses to tetanus increased only after immunization and enhanced responses to HIV-1 p24 antigen were not observed.Conclusions: Immune restoration was incomplete in patients who started HAART with moderately advanced HIV-1 disease and most changes occurred during the first year. These data suggest that this degree of suppression of HIV-1 replication alone will not suffice to restore immune competence. The clinical significance of incomplete reconstitution of CD4 lymphocyte number, phenotype, and proliferative function in HIV-1 infection remains to be determined. (C) 2002 Lippincott Williams & Wilkins.

This exploratory analyses characterizes patterns of lymphocyte recovery in HIV-1-infected patients treated with highly active antiretroviral therapy (HAART) and investigates their relationship with baseline indices and virologic responses. We modeled kinetics of total CD4(+) lymphocytes, as well as naive (CD45RA(+)CD62L(+)), and memory (CD45RA(-)CD45RO(+)) subsets in 48 patients treated with AZT/3TC/Ritonavir for 48 weeks in ACTG protocol 315. Cell kinetic indices were estimated by nonlinear regression methods and were correlated with baseline factors and virologic responses. Five different kinetic patterns were identified, including biphasic growth, growth-plateau, growth-depletion, decay-recovery, and biphasic decay. Although overall mean lymphocyte responses showed a biphasic increase in cell number, a careful investigation reveals that only one-third of patients actually followed the biphasic growth pattern in CD4(+) cell response, while 44% of 48 patients from this study followed the growth-depletion pattern. CD4(+) cell recovery during the first phase and the 48-week study period were negatively correlated with baseline CD4(+) cell counts, and positively correlated with baseline viral load. Memory CD4(+) cell recovery during the first phase was also negatively correlated with baseline memory CD4(+) and total CD4(+) cell number, but the recovery rate of memory CD4(+) cells during the second phase was positively correlated with baseline CD4(+) cell number. Patients with a decay in CD4(+) cell count during treatment were more likely to have experienced virological rebound (58%) than patients with nondecay patterns (24%). The rate and magnitude of the absolute increase in total CD4(+) and memory CD4(+) cell number (but not naive CD4(+) cells) during the second phase were lower in patients with viral rebound compared with patients with persistent viral suppression. These results show that the kinetics of lymphocyte reconstitution in response to potent antiretroviral therapy in individual patients vary considerably from the "classic" biphasic increase that characterizes the mean or median response pattern. Pattern analysis of lymphocyte kinetics may be useful for testing relationships among factors that modulate the response to treatment.

BACKGROUND:The optimal antiretroviral treatment for patients who have human immunodeficiency virus (HIV) viremia despite treatment with nucleoside reverse-transcriptase inhibitors (nucleoside analogues) remains uncertain. We studied treatment with regimens that combined two nucleoside analogues, at least one of which was new, with the protease inhibitor nelfinavir, the nonnucleoside reverse-transcriptase inhibitor efavirenz, or both.METHODS:The study included 195 patients who had been treated with nucleoside analogues only, and had a plasma HIV type 1 (HIV-1) RNA level of at least 500 copies per milliliter. Patients were randomly assigned to receive, in addition to two nucleoside analogues, nelfinavir, efavirenz, or nelfinavir plus efavirenz. The primary end point was a plasma HIV-1 RNA level of less than 500 copies per milliliter at week 16. A secondary end point was the composite of the HIV-1 RNA levels measured at weeks 40 and 48.RESULTS:At week 16 and at weeks 40 and 48, the proportions of patients in whom a plasma HIV-1 RNA level of less than 500 copies per milliliter was achieved were, respectively, 81 percent and 74 percent in the nelfinavir-plus-efavirenz group, 69 percent and 60 percent in the efavirenz group, and 64 percent and 35 percent in the nelfinavir group. Quadruple therapy resulted in a higher rate of viral suppression in both the short term (P=0.03) and the long term (P=0.001) than did triple therapy with nelfinavir. Triple therapy with efavirenz conferred a higher rate of long-term suppression than triple therapy with nelfinavir (P=0.004). Quadruple therapy also achieved a higher rate of virologic suppression than triple therapy with efavirenz (P=0.008).CONCLUSIONS:In HIV-infected patients previously treated with nucleoside analogues, treatment with nelfinavir plus efavirenz and at least one new nucleoside analogue achieves a higher rate of viral suppression than do regimens with nucleoside analogues and nelfinavir or efavirenz alone.

The effects of 1 year of zidovudine, lamivudine, and ritonavir treatment on immune reconstitution were evaluated in 34 human immunodeficiency virus (HIV)-infected individuals. After 48 weeks of therapy, 20 (59%) subjects had <100 copies HIV RNA/mL. CD4+ T cells increased from a median of 192/mm3 at baseline to 362/mm3 at week 48. Lymphocyte proliferative responses to Candida normalized within 12 weeks, but responses to HIV and tetanus remained depressed throughout therapy. Alloantigen responses increased within 12 weeks and then declined to baseline levels. Recovery of delayed-type hypersensitivity responses occurred after 12 weeks for Candida and after 48 weeks for mumps. The magnitude of virologic suppression was correlated with numeric increases in CD4+ T cells, but not with measures of functional immune reconstitution. Plasma virus suppression <100 copies/mL was not significantly correlated with increases in CD4+ T cells or functional immune reconstitution.

Human immunodeficiency virus (HIV)-infected subjects receiving zidovudine were randomized either to add stavudine (d4T) or didanosine (ddI) to their current regimen or to switch to ddI or d4T monotherapy. After 16 weeks of therapy, the mean reduction in HIV RNA from baseline was 0.14 log(10) copies/mL in patients receiving d4T or zidovudine plus d4T. In subjects receiving ddI or ddI plus zidovudine, reductions were 0.39 and 0.56 log(10), respectively. CD4 cell counts remained stable or showed modest increases in all arms except the zidovudine plus d4T arm. Patients receiving zidovudine plus d4T showed progressive declines in CD4 cell counts with a median of 22 cells/mm(3) below baseline by 16 weeks. Examination of intracellular levels of d4T-triphosphate in 6 subjects was consistent with previous in vitro studies demonstrating pharmacologic antagonism between zidovudine and d4T. Analysis of these data suggests that zidovudine and d4T should not be prescribed in combination and that ddI provides greater antiviral activity than d4T in zidovudine-treated patients.

The effect of baseline drug resistance mutations on response to zidovudine, lamivudine, and ritonavir was evaluated in zidovudine-experienced persons infected with human immunodeficiency virus type 1 (HIV-1). Presence of the K70R mutation was associated with significantly higher plasma HIV-1 RNA levels at baseline. However, presence of resistance mutations did not affect the increase in plasma HIV-1 RNA during a 5-week drug washout, nor was there any effect on first-phase virus decay rates after initiation of therapy or on the probability of having plasma HIV-1 RNA levels <100 copies/mL at week 48. Polymorphisms at protease codons 10, 36, and 71 were associated with significantly faster second-phase decay rates. Suppression of plasma HIV-1 RNA despite presence of zidovudine resistance mutations implies that the presence of these mutations does not preclude a durable response to treatment with a potent 3-drug regimen.

Objective: To evaluate patients with cytomegalovirus (CMV) retinitis treated with intravenous cidofovir for long-term outcomes.Design: Patients with CMV retinitis enrolled in a randomized, controlled clinical trial of intravenous cidofovir as treatment for retinitis were followed for long-term outcomes, including 21 patients initially enrolled in the deferral group who received cidofovir therapy after progression of retinitis.Setting: Thirteen tertiary care clinics specializing in AIDS care and ophthalmology.Participants: Fifty-eight patients with AIDS and small peripheral CMV retinitis lesions.Interventions: Cidofovir 5 mg/kg once weekly for 2 weeks followed by low-dose maintenance cidofovir therapy (3 mg/kg) in 35 patients or high-dose maintenance (5 mg/kg) in 23 patients.Main outcome measures: Time to progression of retinitis, drug toxicities.Results: Median time to progression of retinitis was 2.5 months. Median time to discontinuation of cidofovir because of intolerance was 6.6 months, and did not differ significantly between the two maintenance doses. Median time to discontinuation of cidofovir for intolerance other than probenecid reaction was 16.3 months for patients treated with low-dose maintenance and 5.0 months for patients treated with high-dose maintenance (P = 0.021). Proteinuria of 2+ or more occurred at a rate of 1.22/person year. In patients with sufficient follow-up to determine resolution of proteinuria, 89.9% of episodes resolved, and the median time to resolution was 20 days. Rates of probenecid intolerance and of cidofovir-associated uveitis were 0.35/person-year, and 0.20/person-year, respectively.

The effect of baseline drug resistance mutations on response to zidovudine, lamivudine, and ritonavir was evaluated in zidovudine-experienced persons infected with human immunodeficiency virus type 1 (HIV-1). Presence of the K70R mutation was associated with significantly higher plasma HIV-1 RNA levels at baseline. However, presence of resistance mutations did not affect the increase in plasma HIV-1 RNA during a 5-week drug washout, nor was there any effect on first-phase virus decay rates after initiation of therapy or on the probability of having plasma HIV-1 RNA levels <100 copies/mL at week 48. Polymorphisms at protease codons 10, 36, and 71 were associated with significantly faster second-phase decay rates. Suppression of plasma HIV-1 RNA despite presence of zidovudine resistance mutations implies that the presence of these mutations does not preclude a durable response to treatment with a potent 3-drug regimen.

ObjectivesTo ascertain if immunization results in the restoration of responses to recall antigens, in the development of responses to presumed neoantigens, and to identify the virologic and immunologic correlates of these responses in persons with HIV-1 infection. Design and settingOpen-label study carried out at three university-affiliated AIDS Clinical Trials Units in the United States. Subjects and methodsThirty-one subjects participating in AIDS Clinical Trials Group Protocol 375 who had received zidovudine, lamivudine, and ritonavir for at least 48 weeks. Subjects were immunized with tetanus toxoid (TT) at entry and with inactivated hepatitis A vaccine (hep A) and keyhole limpet hemocyanin (KLH) at entry and 6 weeks. The development of antibody, lymphocyte proliferative assay (LPA), and delayed-type hypersensitivity (DTH) responses after immunization were monitored. ResultsThe LPA and DTH responses to TT improved in 57 and 68% of participants, respectively; 73 and 65% developed enhanced LPA and DTH responses to KLH. Forty-eight percent of patients developed a four-fold increase in antibody concentration to tetanus. Seventy-three percent of patients without detectable hepatitis A antibodies at baseline developed antibodies after immunization. Eighty-three percent of patients experienced at least a four-fold rise in KLH antibody concentration. Immune activation and viral load predicted poor recall responses and the number of memory CD4+ T-cells predicted good responses to recall antigens. Naïve CD4+ T-cell numbers, decrease in viral load, increases in CD4+ and CD28+ cells, and decreases in immune activation were associated with responses to presumed neoantigens. ConclusionsMost HIV-infected patients treated with potent combination antiretrovirals develop responses to recall and presumed neoantigens after immunization. Functional immune restoration in response to immunization is related to control of viral replication, decreased immune activation as well as to both quantitative and qualitative restoration of circulating T- lymphocyte subpopulations.

Studies of HIV-1 viral dynamics have shown that HIV-1 replicates in cells producing over 1 billion viral particles per day. 1 Ho DD Heumann AU Perelson AS Chen W Leonard JM Markowitz M Rapid turnover of plasma virions and CD4 lymphocytes in HIV-1 infection. Nature. 1995; 373: 123-126 Crossref PubMed Scopus (3843) Google Scholar Highly active antiretroviral treatment (HAART) reduces the amount of HIV-1 RNA in plasma within several weeks. Viral reservoirs, however, exist in cells within lymph nodes and tonsils that contribute to a second order of viral decay. 2 Cavert W Notermans DW Staskus K et al. Kinetics of response in; lymphoid tissues to antiretroviral therapy of HIV-1 infection. Science. 1997; 276: 960-964 Crossref PubMed Scopus (509) Google Scholar Cellular reservoirs of HIV-1 that remain in spite of effective treatment may reconstitute the viral burden to pre-treatment levels after treatment failure or non-compliance. 3 Wong JK Hezareh M Gunthard HF et al. Recovery of replication-competent HIV despite prolonged suppression of plasma viremia. Science. 1997; 278: 1291-1295 Crossref PubMed Scopus (1840) Google Scholar

Changes in mean telomeric terminal restriction fragment (TRF) length were examined as a marker for cellular replicative history in HIV-1-infected individuals after institution of anti-retroviral therapy (ART). Increases in mean T cell TRF lengths were observed in most patients following therapy; however, the contribution of individual T cell subsets was complex. An elongation of CD8+ T cell TRF was nearly uniformly observed while changes in mean TRF length in CD4+ T cells were heterogeneous as, despite potent suppression of viral replication, CD4 cell telomeres recovered in some patients, yet continued to decline in others. Increases in CD8 cell TRF correlated with decreased memory cells, suggesting a negative selection in the periphery for CD8 cells with extensive replicative history. In contrast, increases in CD4+ T cell TRF length correlated with increases in naive cell subsets, suggesting that the CD4+ T cell TRF increase may reflect a thymic contribution in some patients. These are the first increases in somatic cell telomere length in a population of cells observed in vivo, and the findings are compatible with therapy-induced reconstitution of the lymphoid compartment with cells having a more extensive replicative potential. These findings further distinguish lymphocytes from other somatic cell populations where only decreases in TRF over time have been noted. Thus, institution of ART in persons with moderately advanced HIV-1 disease reveals distinct population dynamics of CD4 and CD8 T cell subsets and also shows that the lymphocyte replicative history is dynamic.