Multisite comparison of methods for the quantitation of the surface expression of CD38 on CD8+ T lymphocytes

Dissociation of CD154 and cytokine expression patterns in CD38+ CD4+ memory T cells in chronic HIV-1 infection

Expression of the activation antigen CD38 on T cells is a strong predictor of the risk of HIV disease progression, but it is not known whether CD38 is a marker or mediator of dysfunction. We examined the relationship between CD38 expression and responses to T-cell receptor stimulation in central memory and effector memory CD4 T cells in HIV-infected persons and in healthy controls. Basal CD38 expression was preserved by blocking golgi transport with brefeldin A. Intracellular expression of interleukin 2, interferon γ, and CD154 was measured after stimulating peripheral blood mononuclear cells with the superantigen staphylococcal enterotoxin B with or without anti-CD28 costimulation. Interferon-γ responses were comparable or increased in stimulated CD38 memory cells, and the interleukin 2 responses of costimulated CD38 central memory cells were decreased in HIV infection. In CD38 cells and especially in CD38 cells of HIV-infected persons, stimulated memory cells more often failed to express CD154 (CD40 ligand) when induced to express cytokine. A dissociated cytokine and CD154 expression by memory CD4 T cells may impair interactions between T cells and antigen-presenting cells, contribute to impaired immunity and help explain the relationship between CD38 expression and disease progression in chronic HIV infection.

Close association of CD8+/CD38 bright with HIV-1 replication and complex relationship with CD4+ T-cell count

BACKGROUND

Measuring lymphocyte activation provides information in addition to CD4(+) T-cell count for immune monitoring of HIV-1 infected patients. CD38 is a well-established activation marker that is generally analyzed on the whole population of CD8(+) T-cells. Focusing specifically on CD38 high expression (CD8(+)/CD38(bright)) may be an interesting surrogate gating strategy because CD38(bright) characterizes principally activated memory cells.

METHODS

CD8(+)/CD38(bright) was investigated in 1,353 HIV-1 infected patients over a one-year period to establish relevant cutoff values and clarify the relationships of this marker with HIV-1 RNA viral load (VL) and CD4(+) T-cell count.

RESULTS

The CD8(+)/CD38(bright) (>8,500 CD38 binding site per cells) is well correlated with HIV-1 VL (r = 0.87, P < 0.001) in this longitudinal follow-up of nonimmunodepressed patients that initiated antiviral therapy (ART). In aviremic patients on ART, the marker was highly predictive of VL rebound (sensitivity 93%, specificity 64% for a VL level of detection >200 copies/ml). While the CD8(+)/CD38(bright) moderately correlated with CD4(+) T-cell count independently of the VL (r = -0.37, P < 0.001), it increased dramatically in aviremic patient groups that exhibited profound CD4(+) T-cell depletion (median 39% for CD4(+) T-cell counts <50/mm(3)). This result indicates that other additional immunological and/or viral factors than readily detectable HIV-1 replication appears to be involved in T-cell activation of immunodepressed individuals.

CONCLUSIONS

CD8(+)/CD38(bright) is an effective marker for monitoring T-cell activation, which is a central factor of HIV-1 pathogenesis. This gating strategy requires only a single additional staining in conventional four color CD4 protocols.

CD13 and CD10 expression of granulocytes as markers for the functioning of the immune system: quantification of the expression of membrane molecules using 1:1 labeled monoclonal antibodies and flow cytometry

HLA-DR expression on monocytes as a marker for the functioning of the immune system is known to be severely depressed in immunodeficiency. Up to now, other markers for the function of the immune system are scarce. In the peripheral blood of patients with open heart surgery the expression of the membrane peptidases neprilysin/CD10 and aminopeptidase N/CD13, was determined on granulocytes in comparison to the monocytic HLA-DR expression. We used the QuantiBRITE flow cytometry system, which yields an absolute antigen expression value (antibodies bound per cell) and may be useful in standardizing surface antigen expression analysis. This system makes use of a highly purified phycoerythrin-labeled antibody with a 1:1 fluorochrome-to-protein ratio, and multilevel calibrated beads with known absolute phycoerythrin fluorescence. Our results show that both membrane peptidases on granulocytes show a similar time-course of expression after heart surgery as do HLA-DR molecules on monocytes, with a decrease from days one to three and a subsequent recovery to normal values. In future analyses a possible relationship between the immunodeficiency of patients and a diminished expression of both membrane peptidases on granulocytes has to be investigated.

Relationship between CD38 expression on peripheral blood T-cells and monocytes, and response to antiretroviral therapy: A one-year longitudinal study of a cohort of chronically infected ART-naive HIV-1+ patients

BACKGROUND

HIV-1 infection has been associated with high expression of CD38 on peripheral blood (PB) CD8+ and CD4+ T-cells, which has been related with poor prognosis in untreated HIV-1+ patients. In turn, CD38 expression on PB monocytes from HIV-1+ individuals and its behavior after starting antiretroviral therapy (ART) have been poorly studied.

METHODS

CD38 expression on PB CD8+ and CD4+ T-lymphocytes and monocytes was prospectively analyzed in 30 ART-naive HIV-1+ patients, using a quantitative multiparameter flow cytometry approach. Patients were tested prior to therapy, and at weeks +2, +4, +8, +12, and +52 after ART.

RESULTS

Prior to ART, CD38 expression was significantly increased on PB CD8+ and CD4+ T-cells and monocytes; despite a significant decrease after ART, CD38 expression remained abnormally high on PB CD8+ T-cells and monocytes, even after one year of therapy, in the absence of detectable plasma viral load. The ART-induced early changes on CD38 expression by PB T-cells and monocytes differed among the cell subsets analyzed and patient groups, probably reflecting an interaction between the direct effects of therapy and a redistribution of the PB compartments of T-cells and monocytes. Hierarchical clustering analysis showed that the overall pattern of changes in CD38 expression observed early after starting ART was predictive of a better response to therapy, not only for PB CD8+ T-cells, but also for CD4+ T-cells and monocytes. Accordingly, those HIV-1+ patients, who experienced a more pronounced increase in CD38 expression on both PB CD4+ T-cells and monocytes after 2 weeks of ART, showed a more rapid viral clearance, which might reflect decreased HIV-1 replication in lymph nodes and other tissues, and a partial restoration of hematopoiesis.

CONCLUSIONS

Combined quantitative measurement of CD38 expression on PB monocytes, and CD8+ and CD4+ T-cells is a more useful tool for monitoring HIV-1+ patients under ART, rather than quantitation of CD38 expression on PB CD8+ T-lymphocytes alone.

Lymphocyte subsets in healthy children from birth through 18 years of age

BACKGROUND

Peripheral blood lymphocyte subsets need to be determined in a large, urban, minority-predominant cohort of healthy children to serve as suitable control subjects for the interpretation of the appearance of these cells in several disease conditions, notably pediatric HIV-1 infection.

OBJECTIVE

We sought to determine the distribution of lymphocyte subsets in healthy urban-dwelling infants, children, and adolescents in the United States.

METHODS

Lymphocyte subsets were determined by means of 3-color flow cytometry in a cross-sectional study of 807 HIV-unexposed children from birth through 18 years of age.

RESULTS

Cell-surface marker analysis demonstrated that age was an extremely important variable in 24 lymphocyte subset distributions measured as percentages or absolute counts--eg, the CD4 (helper) T cell, CD8 (cytotoxic) T cell, CD19 B cell, CD4CD45RACD62L (naive helper) T cell, CD3CD4CD45RO (memory helper) T cell, CD8HLA-DRCD38 (activated cytotoxic) T cell, and CD8CD28 (activation primed cytotoxic) T cell. The testing laboratory proved to be an important variable, indicating the need for using the same laboratory or group of laboratories to assay an individual's blood over time and to assay control and ill or treated populations. Sex and race-ethnicity were much less important.

CONCLUSION

The results of this study provide a control population for assessment of the effects of HIV infection on the normal development and distribution of lymphocyte subsets in children of both sexes, all races, and all ethnic backgrounds from birth through 18 years of age in an urban population. This study's findings will also prove invaluable in interpreting the immune changes in children with many other chronic diseases, such as primary immunodeficiency, malignancy, rheumatoid arthritis, and asthma.

CD38 expression on CD8(+) T cells as a prognostic marker in vertically HIV-infected pediatric patients

Increased expression of CD38 on CD8(+) T cells is associated with activation of the immune system, progression of HIV disease, and death in adults. The prognostic significance of these cells in HIV-infected children, where the picture is complicated by age-related differences in CD38 expression, remains controversial. Measuring the unimodal expression of CD38 on CD8(+) T cells in adults and children by flow cytometry is best accomplished by quantitating the antigen on the cell surface. To our knowledge, this technique has not previously been reported in a pediatric population. Vertically HIV-infected children were age matched for mild (n = 26) and severe (n = 23) clinical disease. Eleven age-matched HIV-negative controls were included for comparison. Quantitation of CD38 on CD8(+) T cells was performed at baseline and 1 y later. The ages of the children in the three clinical groups did not differ significantly (p = 0.6004). HIV-infected children had significantly increased CD38 measurements in comparison with the HIV-negative controls (p = 0.0131), and the severe disease group tended to have higher measurements than the mild disease group. Increased CD38(+)CD8(+) T cells were significant predictors of death within the first year (p = 0.043). These findings support the view that increased CD38 expression on CD8(+) T cells has the same prognostic significance in pediatric as in adult HIV disease.