Effects of HIV-1 infection on lymphocyte phenotypes in blood versus lymph nodes.

Most immunopathogenesis studies of HIV-1 use peripheral blood. Most lymphocytes reside in lymphoid tissues, however, and the extent to which blood mirrors tissues is unclear. Here, we analyze lymphocytes in blood and lymph nodes of HIV-1-uninfected and -infected persons. Baseline comparison of node and blood lymphocytes in seronegative persons demonstrates a lower ratio of CD8+ versus CD4+ T lymphocytes, a lower number of effector cells (CD28-) within the CD8+ compartment, and greater activation (D-receptor [DR+]) within the CD4+ compartment. In infected versus uninfected persons, nodes exhibit elevated CD8+ T lymphocytes with an increased memory-effector phenotype (CD62L-/CD45RA-) and activation (CD38+ and DR+) but minimal differences in the CD4+ compartment. Changes attributable to HIV-1 infection are markedly greater in node lymphocytes than in blood. Comparisons of CD8+ T-lymphocyte parameters and viremia in infected persons reveal positive correlations of CD38+ expression on cells in blood and nodes and a negative correlation of terminal effector cells (CD62L-/CD45RA+) in the nodes to viremia. Multiple linear regression analysis indicates that CD38 expression on node (not blood) CD8+ T lymphocytes is the sole independent predictor for viremia. Thus, blood indirectly reflects processes in lymphoid tissues, and caution should be applied when interpreting immunopathogenesis studies of blood.

Persistent alterations in the T-cell repertoires of HIV-1-infected and at-risk uninfected men.

OBJECTIVE: We examined the association between immunogenic exposure and T-cell receptor (TCR) diversity to more clearly assess the impact of HIV-1 infection on the T-cell repertoire. METHODS: : To estimate the extent of T-cell clonality attributable to HIV-1 infection, we evaluated T-cell repertoires in low-risk and at-risk seronegative men and HIV-1 seropositive men by assessment of T-cell receptor beta-chain (TCR beta) complimentary determining region 3 (CDR3) lengths. RESULTS: The frequency of T-cell clonality in both HIV-1 infected and at-risk uninfected men was elevated in comparison to low-risk uninfected men. Among low-risk and at-risk seronegative, and HIV-1 seropositive men, clonal expansions were present in 3, 8, and 10% of CD4+ CDR3 lengths, and 18, 22, and 28% of CD8+ CDR3 lengths respectively. In addition, the longitudinal conservation of clonal expansions was observed in at-risk seronegative men. Based on comparisons to at-risk seronegative men, we estimate that at-risk seropositive men with chronic HIV-1 infection exhibit a 27% increase in the number of expanded CD8+ CDR3 lengths. CONCLUSION: These findings provide an approximation of the magnitude of the T-cell response in individuals undergoing chronic HIV-1 infection and demonstrate a significant association between the history of immunogenic challenge and the magnitude of clonality within the T-cell repertoire. In addition, these findings underscore the necessity of selecting controls with similar antigenic exposure histories when investigating T-cell dynamics in HIV-infected individuals.

Immunologic profile of highly exposed yet HIV type 1-seronegative men.

The host immune factors that determine susceptibility to HIV-1 infection are poorly understood. We compared multiple immunologic parameters in three groups of HIV-1-seronegative men: 14 highly exposed (HR10), 7 previously reported possibly to have sustained transient infection (PTI), and a control group of 14 low risk blood bank donors (BB). Virus-specific cellular immune assays were performed for CD4(+) T helper cell responses, CD8(+) cytotoxic T lymphocyte activity, CD8(+) cell chemokine release, and CD8(+) cell-derived antiviral soluble factor activity. General immune parameters evaluated included CCR5 genotype and phenotype, interferon alpha production by PBMCs, leukocyte subset analysis, and detailed T lymphocyte phenotyping. Comparisons revealed no detectable group-specific differences in measures of virus-specific immunity. However, the HR10 group differed from the BB group in several general immune parameters, having higher absolute monocyte counts, higher absolute CD8(+) T cell counts and percentages, lower naive and higher terminal effector CD8(+) cells, and lower levels of CD28(+)CD8(+) cells. These changes were not associated with seropositivity for other chronic viral infections. The PTI men appeared to have normal levels of monocytes and slightly elevated levels of CD8(+) T cells (also with increased effector and decreased naive cells). Although we cannot entirely exclude the contribution of other chronic viral infections, these findings suggest that long-lived systemic cellular antiviral immunity as detected by our assays is not a common mechanism for resistance to infection, and that resistance may be multifactorial. General immune parameters reflected by CD8(+) T cell levels and activation, and monocyte concentrations may affect the risk of infection with HIV-1, and/or serve as markers of exposure.

MaGiK method of T-Cell receptor repertoire analysis.

T-cell receptor diversity enables the cellular immune response to recognize a broad range of viral and other pathogenic agents. An increasingly common method of characterizing T-cell receptor diversity and usage in response to antigenic challenges involves the identification of clonal expansions by PCR amplification of the CDR3 region of distinct TCRVbeta families. Though clonal expansions often appear evident upon visual inspection of the results, a systematic method is needed for the valid enumeration of these expansions. Here, we describe a novel analysis method, termed the MaGiK method, for systematically identifying and enumerating clonal T-cell expansions and for applying the results to investigations of the T-cell receptor repertoire.

Predictive value of immunologic and virologic markers after long or short duration of HIV-1 infection.

Laboratory markers that predict HIV-1 disease progression include plasma viral burden, CD4+ T-cell count, and CD38 expression on CD8 T cells. To better understand whether the predictive value of these markers is dependent on how long an individual has been infected, we analyzed data from the Multicenter AIDS Cohort Study early (median = 2.8 years) and late (median = 8.7 years) in the course of infection. Overall, we found that HIV RNA and CD38 levels were similarly predictive of AIDS early on compared with a relatively weaker CD4 cell count signal. Later in the course of infection, CD38 level remained the strongest predictive marker and CD4 cell count registered a marked increase in prognostic power. Among untreated individuals, there was little difference in prognosis (median time to AIDS) associated with given marker values regardless of infection duration. The prognosis given a specific viral load level tended to deteriorate late in the course of infection among those undergoing treatment with monotherapy or combination therapy, however. These data provide a unique historical look at the predictive value and prognostic significance of HIV-1 disease markers at different stages of infection in a large cohort, with direct relevance to current patients who are untreated or for whom treatment is ineffective.