Search

Socioeconomic disadvantage may contribute to poor health through immune-related biological mechanisms. We examined the associations between socioeconomic status, as measured by annual household income, and T-cell markers of aging, including the ratios of CD4 and CD8 effector cells to naïve cells (E/N ratio) and the CD4/CD8 T-cell ratio. We hypothesized that participants with a lower income would have higher E/N ratios and lower CD4/CD8 ratios compared with participants with a higher income, and that these associations would be partially mediated by elevated cytomegalovirus (CMV) IgG antibody levels, a virus implicated in aging and clonal expansion of T cells.Data were from 79 individuals who participated in the population-based Detroit Neighborhood Health Study. We used linear regression to quantify the association between a $10,000 decrease in income and each ratio outcome.After adjustment for age, sex, race, smoking, medication use, and lifetime history of mental health conditions, lower income was associated with a 0.41 (95% confidence interval = 0.09-0.72) log-unit increase in the CD4 E/N ratio and a 0.20 (95% confidence interval = 0.02-0.39) log-unit increase in the CD8 E/N ratio. CMV immunoglobulin G antibody level partially mediated these associations.Our study suggests that low socioeconomic status is associated with immunological aging as measured by the E/N ratio and that impaired immune control of CMV may partially mediate these associations.

In mice, injection of messenger RNA (mRNA) coding for tumor-associated antigens can induce antitumor immune responses and therefore offers a broadly applicable immunotherapy approach. We injected intradermally protamine-stabilized mRNAs coding for Melan-A, Tyrosinase, gp100, Mage-A1, Mage-A3, and Survivin in 21 metastatic melanoma patients. In 10 patients keyhole limpet hemocyanin (KLH) was added to the vaccine. Granulocyte macrophage colony-stimulating factor was applied as an adjuvant. Endpoints were toxicity and immune responses. No adverse events more than grade II have been observed. During treatment the frequency of Foxp3+/CD4+ regulatory T cells was significantly decreased upon mRNA vaccination in peripheral blood of the patients in the KLH arm, whereas myeloid suppressor cells (CD11b+HLA-DR lo monocytes) were reduced in the patients not receiving KLH. A reproducible increase of vaccine-directed T cells was observed in 2 of 4 immunologically evaluable patients. One of 7 patients with measurable disease showed a complete response. In conclusion, we show here that direct injection of protamine-protected mRNA is feasible and safe. The significant influence of the treatment on the frequency of immunosuppressive cells, the increase of vaccine-directed T cells upon treatment in a subset of patients together with the demonstration of a complete clinical response encourage further clinical investigation of the protamine-mRNA vaccine.

Chronic myelogenous leukemia (CML) may be amenable to cell-based adoptive immunotherapy, as suggested by the graft-versus-leukemia effect of bone marrow transplantation and the therapeutic benefit of donor leukocyte infusions. Specific adoptive immunotherapy without bone marrow transplantation might be more effective and less cost-intensive. Professional antigen-presenting cells, the dendritic cells, from patients with CML are derived from the malignant clone and may stimulate antileukemia T-cell responses. Autologous T cells may also be able to recognize tumor antigens on CML cells directly. Here, the authors show that CD4 and CD8 T-cell responses to autologous CML cells can be generated in vitro rapidly and effectively by performing modified autologous mixed lymphocyte/tumor cell cultures (MLTC) in serum-free medium in the presence of cytokines known to support dendritic cell differentiation. MLTC-sensitized T cells secreted large amounts of the type 1 cytokine interferon-gamma, as well as interleukin (IL)-2. However, they also secreted a variety of other cytokines, including the type 2-subtype cytokine IL-13 but not the classic type 2 cytokines IL-4, IL-5, and IL-10. Monoclonal populations of CML-specific CD4 cells could be derived from these lines in limited numbers but showed markedly enhanced reactivity. This suggests that CML-specific T cells are relatively rare in these autologous MTLC-derived sensitized populations, but that their isolation and propagation would yield much more potent antitumor effector cells for use in adoptive immunotherapy without the need for bone marrow transplantation.

Organ graft rejection is caused by the recognition of allogeneic MHC molecules by recipient T cells by two different pathways. The indirect pathway of alloreactivity requires the presentation of MHC peptides from the graft by autologous APC, as with conventional antigen. The direct pathway, on the other hand, requires the recognition of foreign MHC on foreign cells. The regulatory mechanisms for this component of alloreactivity have not been extensively studied. We show here that the T cell response activated by alloantigens in the direct pathway is similarly constrained and modulated by cytokines, as has been shown for classic antigen presentation. Thus, the inclusion of IL-2 or TGF-beta in MLC performed with purified responder T cells resulted in outgrowth of cells secreting IL-2 and IFN-gamma, whereas addition of IL-4, IL-10, or anti-TGF-beta encouraged outgrowth of cells secreting IL-4 and IL-10. T cells alloactivated via the direct pathway and then cloned in IL-2 alone secreted IL-4 and IL-10 as well as IFN-gamma and IL-2 (Th0 phenotype). Established clones remained susceptible to cytokine modulation, such that IL-4 and IL-10 decreased their secretion of IL-2 and IFN-gamma, whereas TGF-beta suppressed IL-4 and IL-10 secretion. The first alterations of Th0 toward Th1 or Th2 phenotypes could already be observed after only a very brief exposure to cytokines of 48 hr, followed by extended culture with IL-2 alone. These results confirm that human T cells with Th1 and Th2 phenotypes, recognizing alloantigen via the direct pathway, derive from the same IL-2-secreting precursor and can be manipulated by cytokines in an analogous fashion to conventional antigen-reactive cells. These findings may have implications for manipulating the direct pathway of alloantigen recognition in human organ transplantation.

The specificity of a novel monoclonal antibody (moAB), TU69, directed to the interleukin 2 receptor (IL-2R) was verified by sequential immunoprecipitation with anti-Tac. TU69 cross-competed with anti-Tac in binding analyses. When TU69 was added during the sensitization of normal peripheral blood mononuclear cells (PBMC) to allogeneic HLA-class I or -class II mismatched stimulator PBMC, alloproliferative responses and specific cytotoxicity were no longer detectable and the generation of natural killer (NK)-like effector cells was partially inhibited. Remarkably, however, the generation of CD4+ nonspecific suppressor T cells in such mixed lymphocyte cultures (MLC) was not inhibited--but, in contrast, was strongly enhanced in the presence of TU69. These suppressor cells inhibited unrelated allospecific responses in vitro to background levels even at a ratio of 50:1 responder:irradiated suppressor T cell lines. Such a potent experimental suppressor system suggests a possible application of TU69 for in vivo tolerance induction after transplantation, by down-regulating allospecific effector cells and allowing the generation of tolerance to graft antigens.

The in vitro action of the immunosuppressive agent Cyclospirin A has been investigated using porcine cells. Lymphocyte proliferation induced in response to transplantation antigens and phytohaemagglutinin (PHA), was inhibited by this agent at doses that failed to inhibit mitogenisis in response to sheep anti-pig IgM, growth of kidney cell monolayers, and leukocyte migration.