Restoring immune function of tumor-specific CD4+ T cells during recurrence of melanoma.

Recurrent solid malignancies are often refractory to standard therapies. Although adoptive T cell transfer may benefit select individuals, the majority of patients succumb to their disease. To address this important clinical dilemma, we developed a mouse melanoma model in which initial regression of advanced disease was followed by tumor recurrence. During recurrence, Foxp3(+) tumor-specific CD4(+) T cells became PD-1(+) and represented >60% of the tumor-specific CD4(+) T cells in the host. Concomitantly, tumor-specific CD4(+) T effector cells showed traits of chronic exhaustion, as evidenced by their high expression of the PD-1, TIM-3, 2B4, TIGIT, and LAG-3 inhibitory molecules. Although blockade of the PD-1/PD-L1 pathway with anti-PD-L1 Abs or depletion of tumor-specific regulatory T cells (Tregs) alone failed to reverse tumor recurrence, the combination of PD-L1 blockade with tumor-specific Treg depletion effectively mediated disease regression. Furthermore, blockade with a combination of anti-PD-L1 and anti-LAG-3 Abs overcame the requirement to deplete tumor-specific Tregs. In contrast, successful treatment of primary melanoma with adoptive cell therapy required only Treg depletion or Ab therapy, underscoring the differences in the characteristics of treatment between primary and relapsing cancer. These data highlight the need for preclinical development of combined immunotherapy approaches specifically targeting recurrent disease.

Naive tumor-specific CD4(+) T cells differentiated in vivo eradicate established melanoma.

In vitro differentiated CD8(+) T cells have been the primary focus of immunotherapy of cancer with little focus on CD4(+) T cells. Immunotherapy involving in vitro differentiated T cells given after lymphodepleting regimens significantly augments antitumor immunity in animals and human patients with cancer. However, the mechanisms by which lymphopenia augments adoptive cell therapy and the means of properly differentiating T cells in vitro are still emerging. We demonstrate that naive tumor/self-specific CD4(+) T cells naturally differentiated into T helper type 1 cytotoxic T cells in vivo and caused the regression of established tumors and depigmentation in lymphopenic hosts. Therapy was independent of vaccination, exogenous cytokine support, CD8(+), B, natural killer (NK), and NKT cells. Proper activation of CD4(+) T cells in vivo was important for tumor clearance, as naive tumor-specific CD4(+) T cells could not completely treat tumor in lymphopenic common gamma chain (gamma(c))-deficient hosts. gamma(c) signaling in the tumor-bearing host was important for survival and proper differentiation of adoptively transferred tumor-specific CD4(+) T cells. Thus, these data provide a platform for designing immunotherapies that incorporate tumor/self-reactive CD4(+) T cells.

CD4-positive T lymphocytes provide a neuroimmunological link in the control of adult hippocampal neurogenesis.

Adult hippocampal neurogenesis occurs in an exceptional permissive microenvironment. Neuroimmunological mechanisms might be prominently involved in the endogenous homeostatic principles that control baseline levels of adult neurogenesis. We show in this study that this homeostasis is partially dependent on CD4-positive T lymphocytes. Systemic depletion of CD4-positive T lymphocytes led to significantly reduced hippocampal neurogenesis, impaired reversal learning in the Morris water maze, and decreased brain-derived neurotrophic factor expression in the brain. No such effect of CD8 or B cells was observed. Repopulation of RAG2(-/-) mice with CD4, but not with CD8 cells again increased precursor cell proliferation. The T cells in our experiments were non-CNS specific and rarely detectable in the healthy brain. Thus, we can exclude cell-cell contacts between immune and brain cells or lymphocyte infiltration into the CNS as a prerequisite for an effect of CD4-T cells on neurogenesis. We propose that systemic CD4-T cell activity is required for maintaining cellular plasticity in the adult hippocampus and represents an evolutionary relevant communication route for the brain to respond to environmental changes.

Epidemiologic characteristics of rhinitis in Turkish children: the International Study of Asthma and Allergies in Childhood (ISAAC) phase 2.

Rhinitis is a common problem with important comorbidities. In order to search the association between rhinitis, allergic phenotypes and other risk factors in Turkish children, a parental questionnaire about allergic diseases and risk factors, and skin prick test (SPT) with 13 inhalant allergens were performed in a population-based sample of 2774 children aged 9-11 yr. Bronchoprovocation testing with hypertonic saline (HS)and total IgE analysis were limited to a subsample of 350 children. Rhinitis was defined as a problem with sneezing, rhinorrhea, or nasal congestion when the child did not have a viral respiratory infection. The prevalences of ever rhinitis, current (last 12 months) rhinitis (CR), and ever hay fever were 36.3%, 30.6%, and 8.3%, respectively. SPT positivity rate was 20.4% among children with CR. Current wheezing and flexural dermatitis were significantly associated with CR. CR significantly increased the risk of asthma among both atopic and non-atopic subjects [odds ratio (OR), 3.98; 95% CI, 1.81-8.76; and OR, 2.79; 95% CI, 1.82-4.26, respectively]. The association between CR and bronchial hyperreactivity (BHR) was not significant. The multiple logistic regression analysis revealed family atopy (OR=2.25, 95% CI=1.79-2.83, p<0.001), current indoor heating with gas stove (OR=1.78, 95% CI=1.18-2.64, p=0.006) and dampness/molds at home during the first year of life (OR=1.70, 95% CI=1.25-2.31, p=0.001) as significant risk factors for CR. Turkish school children showed a high prevalence of rhinitis with a preponderance of non-atopics. The highly significant association between rhinitis and asthma independent of atopic sensitization emphasize the importance of non-atopic forms of rhinitis.

Interleukin-2-dependent mechanisms of tolerance and immunity in vivo.

IL-2 is a critical T cell growth factor in vitro, but predominantly mediates tolerance in vivo. IL-2 is mainly produced by CD4(+) Th cells, but the role of Th cell-derived IL-2 in vivo is controversial. We demonstrate that during immunity to a tumor/self-Ag, the predominant role of Th cell-derived IL-2 was to maintain IL-2Ralpha (CD25) on CD4(+) T regulatory cells (T(reg)), which resulted in their maintenance of the T(reg) cell lineage factor, Forkhead/winged helix transcription factor (Foxp3), and tolerance. However, in the absence of T(reg) cells, Th cell-derived IL-2 maintained effector T cells and caused autoimmunity. IL-2R signaling was indispensable for T(reg) cell homeostasis and efficient suppressor function in vivo, but, surprisingly, was not required for their generation, because IL-2(-/-) and CD25(-/-) mice both contained Foxp3(+) T cells in the periphery. IL-2R signaling was also important for CD8(+) T cell immunity, because CD25(-/-) tumor-reactive CD8(+) T cells failed to affect established tumors. Conversely, IL-2R signaling was not required for Th cell function. Lastly, administration of anti-IL-2 plus exogenous IL-15 to tumor-bearing mice enhanced the adoptive immunotherapy of cancer. Therefore, Th cell-derived IL-2 paradoxically controls both tolerance and immunity to a tumor/self-Ag in vivo.

CD8+ T cell immunity against a tumor/self-antigen is augmented by CD4+ T helper cells and hindered by naturally occurring T regulatory cells.

CD4(+) T cells control the effector function, memory, and maintenance of CD8(+) T cells. Paradoxically, we found that absence of CD4(+) T cells enhanced adoptive immunotherapy of cancer when using CD8(+) T cells directed against a persisting tumor/self-Ag. However, adoptive transfer of CD4(+)CD25(-) Th cells (Th cells) with tumor/self-reactive CD8(+) T cells and vaccination into CD4(+) T cell-deficient hosts induced autoimmunity and regression of established melanoma. Transfer of CD4(+) T cells that contained a mixture of Th and CD4(+)CD25(+) T regulatory cells (T(reg) cells) or T(reg) cells alone prevented effective adoptive immunotherapy. Maintenance of CD8(+) T cell numbers and function was dependent on Th cells that were capable of IL-2 production because therapy failed when Th cells were derived from IL-2(-/-) mice. These findings reveal that Th cells can help break tolerance to a persisting self-Ag and treat established tumors through an IL-2-dependent mechanism, but requires simultaneous absence of naturally occurring T(reg) cells to be effective.

The effect of montelukast on allergen-induced cutaneous responses in house dust mite allergic children.

The benefits of a leukotriene modifier on allergen-induced cutaneous responses have not been studied in children. We hypothesized that a leukotriene-receptor antagonist would provide protection against allergen-induced early and/or late phase cutaneous responses in susceptible children. In a randomized, double-blind, placebo-controlled, cross-over study in 6- to 15-year-old house dust mite allergic children, we compared the benefit of either montelukast or a matching placebo for 2 days on cutaneous responses induced by intradermal injection of house dust mite extract. Responses were measured as the mean of the longest diameter and its longest perpendicular of the induration response after 10, 20 min, 4 h and 6 h of the challenge. A total of 30 children were randomized to placebo or montelukast. The mean decline from baseline was significantly greater (p = 0.04) in the montelukast-treated children [-5.20 mm (-12.03-1.63)][median (95% CI)] than in the placebo-treated children [0.13 mm (-6.46-6.73] at 6th hour of the challenge, as was the mean diameter (p = 0.04), but did not differ in the remaining time points. We concluded that in house dust mite allergic children, montelukast 5 mg provided significant improvement in allergen-induced cutaneous late-phase responses, suggesting its contribution to allergic skin responses and its potential therapeutic value.

Increased interleukin-4 and decreased interferon gamma production in children with asthma: function of atopy or asthma?

Both atopy and asthma are claimed to be associated with a Th-2 cytokine pattern. We sought to determine the contribution of atopy and asthma to the observed Th-2/Th-1 imbalance in these conditions. Of 60 children aged 6-16 years that were included in the study, 13 were nonatopic nonasthmatic, 15 atopic nonasthmatic, 14 nonatopic asthmatic, and 18 atopic asthmatic. Atopic children had positive skin prick tests to grass pollens only. All children were studied after an asymptomatic and drug-free period of at least three months. Total IgE was measured in serum. Peripheral blood mononuclear cells were cultured and stimulated in vitro with phytohemagglutinin and interferongamma (IFN-gamma) and interleukin-4 (IL-4) measured in the supernatants. Total IgE was significantly higher in atopic asthmatics compared to nonatopic asthmatics (p = 0.004), and nonatopic nonasthmatics (p = 0.001), but was not different from atopic nonasthmatics (p >0.05). On the other hand, IL-4 was significantly elevated in atopic asthmatics and in nonatopic asthmatics compared to nonatopic nonasthmatics (p = 0.037 and p = 0.009, respectively). Although atopic asthmatics had lower IFN-gamma values than nonatopic asthmatics, the difference did not reach statistical significance. No correlation was detected between any two parameters. Our results suggest that both atopy and asthma contribute to the increased levels of IL-4 and that, whereas nonatopic asthma is associated with increases in both IL-4 and IFN-gamma release by mononuclear cells, only atopic asthma is characterized by a Th-2 type cytokine dominance.