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Biomedical subjects

J Ferbas

Publications and source records attributed to J Ferbas.

13 recordsLinked to original sources
PubMed1996

Rapid evolution of human immunodeficiency virus strains with increased replicative capacity during the seronegative window of primary infection.

The relationship between host and virus was examined during the initial stages of human immunodeficiency virus type 1 (HIV) infection in a volunteer from the Multicenter AIDS Cohort Study (MACS). The individual was asymptomatic and unaware of his infection during an initial donation of blood and inguinal lymphoid tissue. Proviral DNA, however, was present in cells from both sources, HIV RNA was detected in the plasma, and CD4+ cell levels were reduced by approximately 50% compared with previous donations in the MACS. In a second blood donation 12 days later, plasma HIV RNA increased 200-fold in tandem with viral isolates with an increased growth phenotype in vitro. HIV burden was ultimately suppressed upon seroconversion and the emergence of HIV-specific CD8+ cytotoxic T lymphocytes. These observations provide further evidence that the potential benefits of early treatment may be maximized during the early stages of infection, when viral fitness may be low but is unopposed by immune responses.

CD4-Positive T-Lymphocytes↗
PubMed1995

Assessment of aerosol containment on the ELITE flow cytometer.

Biohazardous aerosols generated during cell sorting have been of increased concern recently because of interest in sorting specimens containing human immunodeficiency virus type 1 (HIV-1). Current flow cytometers have features designed to contain such aerosols within the sorting chamber, but the efficacy of these features has not been established. Therefore, we tested aerosol containment by two ELITE flow cytometers (Coulter Cytometry, Inc., Hialeah, FL) during sorting of specimens containing high titers of bacteriophage. Agar plates confluent with susceptible Escherichia coli were used to detect infectious units released from the sorting chamber. Under recommended operating conditions very few infectious units were released from the sorting chambers. Release increased when the center stream was not optimally collected in a vacuum-exhausted tube or the chamber door was not completely closed. Failure of the negative pressure and high efficiency particle air (HEPA) filtration features had less of an effect. The data indicate that these standard safety features provide a rational expectation of safety for the flow cytometry operator.

Aerosols↗
PubMed1995

Failure of T-cell homeostasis preceding AIDS in HIV-1 infection. The Multicenter AIDS Cohort Study.

We and others have postulated that a constant number of T lymphocytes is normally maintained without regard to CD4+ or CD8+ phenotype ('blind' T-cell homeostasis). Here we confirm essentially constant T-cell levels (despite marked decline in CD4+ T cells and increase in CD8+ T cells) in homosexual men with incident human immunodeficiency virus, type 1 (HIV-1), infection who remained free of acquired immunodeficiency syndrome (AIDS) for up to eight years after seroconversion. In contrast, seroconverters who developed AIDS exhibited rapidly declining T cells (both CD4+ and CD8+) for approximately two years before AIDS, independent of the time between seroconversion and AIDS, suggesting that homeostasis failure is an important landmark in HIV disease progression. Given the high rate of T-cell turnover in HIV-1 infection, blind T-cell homeostasis may contribute to HIV pathogenesis through a CD8+ T lymphocytosis that interferes with regeneration of lost CD4+ T cells.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Virus burden in long-term survivors of human immunodeficiency virus (HIV) infection is a determinant of anti-HIV CD8+ lymphocyte activity.

Persons infected with human immunodeficiency virus (HIV) for > 8 years were studied to delineate virologic and immunologic attributes of long-term survival. Whereas those with 300-700 CD4+ cells/microL often had circulating cytotoxic T lymphocytes (CTL) against HIV antigens, those with > 1000 CD4+ cells/microL did not. The subjects with > 1000 CD4+ cells/microL had low virus burden, low levels of Gag-specific CTL precursors, and minimal CD8+ cell activation. Overall, elevated levels of CD8+ cells, CD38 antigen expression on CD8+ cells, and anti-HIV functions were correlated with increased virus burden, provirus load, and HIV plasma RNA levels. A factor that suppressed HIV replication was spontaneously secreted from CD8+ cells of most subjects but not from those with high CD4+ cell counts. CD8+ cell activities, therefore, may reflect chronic viral stimulation of the immune system. Long-term survivors with high levels of CD4+ cells maintained control of viral replication but lacked the CD8+ cell activities.

ADP-ribosyl Cyclase↗
PubMed1995

Selective decrease in human immunodeficiency virus type 1 (HIV-1)-induced alpha interferon production by peripheral blood mononuclear cells during HIV-1 infection.

We previously reported that human immunodeficiency virus type 1 (HIV-1), herpes simplex virus (HSV), and Sendai virus induce higher levels of alpha interferon (IFN-alpha) in blood dendritic cells than in monocytes of healthy donors. In the present study, the levels of IFN-alpha induced by T-cell tropic (IIIb and RF) and monocytotropic (BaL) strains of HIV-1 and by HSV were significantly decreased in peripheral blood mononuclear cells (PBMCs) derived from subjects with asymptomatic and symptomatic HIV-1 infection. In contrast, Sendai virus, a paramyxovirus that induces proportionally more IFN-alpha in monocytes and B cells than do either HIV-1 or HSV, stimulated normal levels of IFN-alpha in PBMCs from the HIV-1-infected men. The IFN-alpha produced by PBMCs from the HIV-1-seropositive subjects was partially acid labile, whereas the IFN-alpha produced by PBMCs from the HIV-1-seronegative donors was acid stable. We hypothesize that there is a selective defect in IFN-alpha production by peripheral blood dendritic cells, whereas the host retains the IFN-alpha-producing capacity of monocytes and B lymphocytes. The loss of IFN-alpha production in response to HIV-1, herpesviruses, and possibly other pathogens could contribute to the progression of HIV-1 infection and to the development of AIDS.

Cells, Cultured↗
PubMed1994

CD8+ lymphocyte activation at human immunodeficiency virus type 1 seroconversion: development of HLA-DR+ CD38- CD8+ cells is associated with subsequent stable CD4+ cell levels. The Multicenter AIDS Cohort Study Group.

Subsets of activated CD8+ lymphocytes defined by membrane expression of the activation antigens HLA-DR and CD38 were counted by three-color flow cytometry in homosexual men who subsequently became seropositive for human immunodeficiency virus type 1 (HIV). Profound CD8+ cell activation was seen in all subjects at seroconversion and 6 and 12 months later. The HLA-DR+ CD38+ CD8+ cell population, which has potent direct HIV cytotoxic T cell activity, was markedly elevated at seroconversion in all subjects. In some men, these levels remained elevated throughout the first year of infection. During the next 5 years, these men had stable CD4+ cell levels, whereas the others did not. Long-term survivors (seropositive for 9 years, > 800 CD4+ cells/mm3) also had elevated levels of this subset, despite few other activated CD8+ cells. Thus, selective elevation of HLA-DR+ CD38- CD8+ cells was a marker of subsequent stable HIV disease.

ADP-ribosyl Cyclase↗
PubMed1993

Evaluation of a dual-color flow cytometry immunophenotyping panel in a multicenter quality assurance program.

A basic immunophenotyping panel that employed dual-color combinations of fluorescein isothiocyanate (FITC) and phycoerythrin (PE) conjugated monoclonal antibodies (mAb; FITC-CD45/PE-CD14, FITC-IgG1/PE-IgG2, FITC-CD3/PE-CD8, FITC-CD3/PE-CD4, FITC-CD3/PE-CD16 + PE-CD56, and PE-CD19) was utilized in a quality assurance program to determine whether the 4 laboratories participating in a multicenter AIDS study obtained similar lymphocyte subset percentage values for T cells, B cells, NK cells, and CD4+ and CD8+ T cells. Over a 1 1/2 year period, 78 shared peripheral blood specimens were prepared and analyzed in each laboratory. The CD45bright CD14- percentage for each specimen was used to correct that individual's lymphocyte subset values. Interlaboratory coefficients of variation (CV) for the human immunodeficiency virus type I (HIV) seronegative (n = 38) and HIV-seropositive (n = 40) specimens using this panel were < 3% for total T cells; < 5% for CD4+ T cells and CD8+ T cells; < or = 17% for B and NK cells; and < 8% for CD4T/CD8T ratios. The 6-tube basic immunophenotyping panel has several notable features: a) for clinical studies, it permits comprehensive evaluation of an individual's major lymphocyte subsets, i.e., T, B, NK, and CD4+ and CD8+ T cells; b) for interlaboratory proficiency testing programs, it allows the detection of differences among laboratories in measurements of several functionally distinct cell populations; and c) for within-sample quality assurance, it provides several quality control checks, including the lymphosum, i.e., the sum of an individual's corrected T+B+NK values, a sum that was generally 100 +/- 5% on the HIV-seronegative specimens analyzed in this study.

AIDS Serodiagnosis↗
PubMed1993

Changes in T and non-T lymphocyte subsets following seroconversion to HIV-1: stable CD3+ and declining CD3- populations suggest regulatory responses linked to loss of CD4 lymphocytes. The Multicenter AIDS Cohort Study.

We investigated changes in lymphocyte subsets (total, CD4+ and CD8+ T cells, as well as non-T cells) associated with human immunodeficiency virus type I (HIV-1) seroconversion in 321 homosexual or bisexual men in the Multicenter AIDS Cohort Study (MACS). These subjects had serial lymphocyte characterizations for up to 4 years before and 5 years after seroconversion. CD4+ lymphocyte levels declined rapidly in the first 18 months following seroconversion and less rapidly thereafter, while CD8 lymphocytes increased with similar kinetics. In contrast, total T (CD3+) lymphocytes declined only slightly in the first 18 months following seroconversion, and then remained stable. These results support the hypothesis of physiologic regulation of the total number of circulating T cells, such that lost CD4+ lymphocytes are replaced by newly generated CD4+ and CD8+ lymphocytes; over time, continued loss of CD4+ lymphocytes due to HIV-1 infection would result in net replacement of lost CD4+ lymphocytes with CD8+ lymphocytes. Non-T (CD3-) lymphocytes also declined after seroconversion, and this decline paralleled that of CD4+ lymphocytes. Thus, changes in both T and non-T lymphocytes after HIV-1 seroconversion may reflect the operation of homeostatic or regulatory mechanisms. Whether these mechanisms contribute to the development of immune deficiency requires further study.

CD3 Complex↗
PubMed1992

Frequent oropharyngeal shedding of Epstein-Barr virus in homosexual men during early HIV infection.

OBJECTIVE: To determine the frequency of Epstein-Barr virus (EBV) oropharyngeal shedding during HIV infection in homosexual men in the Multicenter AIDS Cohort Study. DESIGN: The cohort consisted of 210 men who were HIV-seronegative at their baseline study visit, 39 of whom seroconverted to HIV at a later date, and 73 asymptomatic and mildly symptomatic men with HIV infection of indeterminate duration. METHODS: EBV in throat washings was detected by transformation of newborn cord blood lymphocytes. RESULTS: EBV was isolated from 49% (35 out of 71) of the HIV-seropositive and 16% (33 out of 204) of the HIV-seronegative homosexual men tested at their baseline visit. Elevated EBV shedding frequency was noted 6 months before, as well as during the first HIV-seropositive clinic visit, in the men who seroconverted to HIV. Seronegative men who shed EBV at their baseline visit seroconverted to HIV within a shorter period than did non-shedders during 5 years of follow-up. Shedding of EBV was not significantly associated with either abnormal T-cell numbers, clinical symptoms or risk for development of AIDS. CONCLUSIONS: There is an increased rate of EBV shedding in HIV-seropositive homosexual men that occurs very early in the course of HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Influence of HIV-1 infection and cigarette smoking on leukocyte profiles in homosexual men. The Multicenter AIDS Cohort Study.

The interaction between the effects of HIV-1 infection and cigarette smoking on leukocyte profiles was studied in 307 HIV-1 seroconverters in the Multicenter AIDS Cohort Study (MACS). Longitudinal data for white blood cell (WBC) counts, WBC differentials, T cell subsets, and smoking behavior were collected semiannually for up to 7 years. Prior to seroconversion, total WBC count increased in direct proportion to daily cigarette consumption, but this effect disappeared within 3 years of seroconversion. Analyses of WBC subsets (lymphocytes, monocytes, and granulocytes) and lymphocyte subsets (CD4+, CD8+ and non-T[CD3-]) showed that smoking had only minor effects on the proportions of these cells. In contrast, HIV-1 seroconversion was associated with a dramatic decrease in CD4+ lymphocyte percentage, a large increase in CD8+ lymphocyte percentage, a small increase in total lymphocyte percentage, and small decreases in the non-T lymphocyte and granulocyte percentages. These findings indicate that the effect of smoking on CD4 cell counts is (a) nonspecific, (b) maximal in seronegative individuals; and (c) lost by 3 years after seroconversion. Although the mechanism of the loss of smoking-induced leukocytosis after seroconversion remains to be determined, our results suggest that the effects of smoking are not likely to be important in the clinical use of leukocyte measurements, including measurements of CD4 lymphocytes, in individuals who have been HIV-1 seropositive for more than 3 years.

CD4-CD8 Ratio↗
PubMed1990

Quality control in the flow cytometric measurement of T-lymphocyte subsets: the multicenter AIDS cohort study experience. The Multicenter AIDS Cohort Study Group.

Since 1984, the Multicenter AIDS Cohort Study (MACS) has utilized four flow cytometry laboratories to measure T-lymphocyte subset levels semiannually in a large cohort of homosexual men. This report summarizes the steps taken in the MACS laboratories to attain comparability of lymphocyte subset determinations across the centers and over time. Identical flow cytometers, monoclonal antibodies, and analytic procedures have been used, and over a period of time, the procedure for sample preparation was also standardized. Interlaboratory proficiency testing utilizing identical specimens analyzed in the four laboratories was performed to evaluate the comparability of the data among the laboratories. Our results verify that such testing can identify technical bias in flow cytometric evaluations performed at different laboratories. Temporal laboratory consistency in flow cytometric measurements was evaluated using data from each site's HIV-seronegative homosexual reference group. Both sequential 95% confidence intervals (mean +/- 2 x SEM) and the within-person standard deviations of the immune measurements were considered. Significant variation in CD3, CD4, and CD8 lymphocyte subset percentages over time in the seronegative reference population was observed. Our observations indicate that the lymphocyte subset values of this seronegative group should be used to adjust those obtained on the seropositive study participants during a particular time period, thereby allowing improved discrimination of the effects of HIV on T cells in infected individuals. The data presented are of use for designing epidemiologic and intervention studies in HIV-1-infected individuals, especially for calculating sample sizes. The methods we have used to assess the quality of data in the MACS have general application to quality control programs in flow cytometry laboratories. In particular, comparison of sequential confidence intervals and within-person standard deviations for lymphocyte subset determinations on control populations are essential to a comprehensive proficiency testing program because they permit assessment of consistency within a laboratory over time.

Acquired Immunodeficiency Syndrome↗