Purpose: The success of cancer immunotherapy depends on the balance between effector T cells and suppressive immune regulatory mechanisms within the tumor microenvironment. In this study we investigated whether transient monoclonal antibody-mediated depletion of CD25 high regulatory T cells (Treg) is capable of enhancing the immunostimulatory efficacy of dendritic cell vaccines.Experimental Design: Thirty HLA-A2.1 + metastatic melanoma patients were vaccinated with mature dendritic cells pulsed with tumor peptide and keyhole limpet hemocyanin (KLH). Half of the patients were pretreated with daclizumab, a humanized antibody against the interleukin-2 (IL-2) receptor α-chain (CD25), either four or eight days before dendritic cell vaccinations. Clinical and immunologic parameters were determined.Results: Daclizumab efficiently depleted all CD25 high immune cells, including CD4 + FoxP3 + CD25 high cells, from the peripheral blood within four days of administration. Thirty days after administration, daclizumab was cleared from the circulation and all CD25 + cells reappeared. The presence of daclizumab during dendritic cell vaccinations prevented the induction of specific antibodies in vivo but not the presence of antigen-specific T cells. Daclizumab, however, did prevent these CD25 + T cells from acquiring effector functions. Consequently, significantly less patients pretreated with daclizumab developed functional, vaccine-specific effector T cells and antibodies compared with controls. Daclizumab pretreatment had no significant effect on progression-free survival compared with the control group.Conclusions: Although daclizumab depleted the CD4 + FoxP3 + CD25 high Tregs from the peripheral circulation, it did not enhance the efficacy of the dendritic cell vaccine. Residual daclizumab functionally suppressed de novo induced CD25 + effector cells during dendritic cell vaccinations. Our results indicate that for immunotherapeutic benefit of transient Treg depletion, timing and dosing as well as Treg specificity are extremely important. Clin Cancer Res; 16(20); 5067-78. ©2010 AACR.Melanoma is considered one of the most immunogenic types of cancers. This is based on the following arguments: (a) several melanoma-specific antigens have been identified (1, 2); (b) functional lymphocytes specific for melanoma antigens are increased in melanoma patients (3); (c) immune-stimulating agents can have a positive effect on disease outcome (4, 5); and (d) spontaneous melanoma regressions with simultaneous onset of vitiligo have been reported (6).Immunotherapeutic clinical trials have succeeded in expanding melanoma-specific effector T cells in vivo, but favorable outcomes are still limited because tumor-induced mechanisms of immune evasion may render the host tolerant for melanoma antigens (7,8). Immunosuppression at the tumor microenvironment mediated by regulatory T cells (Treg) is one of the most critical mechanisms of tumor-immune escape and a major hurdle for successful immunotherapy (9-11).In melanoma patients, selective...

An accurate prediction of the prognosis of patients with idiopathic membranous nephropathy (iMN) should allow restriction of immunosuppressive treatment to patients who are at highest risk for ESRD. On the basis of retrospective studies, it has previously been suggested that the urinary excretions of ␤2-microglobulin (U␤2m) and IgG (UIgG) are useful predictors of renal insufficiency in patients with iMN. The threshold values of 0.5 g/min (U␤2m) and 250 mg/24 h (UIgG) have been validated in a new and larger patient cohort. From 1995 onward, 57 patients with iMN (38 men, 19 women; age 48 ؎ 16 yr), a nephrotic syndrome, and a serum creatinine level <1.5 mg/dl were studied prospectively. At baseline, a standardized measurement was carried out to determine renal function and protein excretion. The end point renal death was defined as a serum creatinine exceeding 1.5 mg/dl or a rise of serum creatinine of >50%. Mean (؎SD) follow-up was 53 ؎ 23 mo. Thus far, 25 (44%) of the patients have reached the end point renal death. Multivariate analysis confirmed U␤2m as the strongest independent predictor for the development of renal insufficiency. Sensitivity and specificity were 88 and 91%, respectively, for U␤2m, and both were 88% for UIgG. When the excretions of both proteins were combined, specificity improved to 97%. It is concluded that the present data validate the accuracy of U␤2m and of UIgG in predicting renal outcome in patients with iMN. These markers can be used to guide decisions on the start of immunosuppressive treatment.

Plasmacytoid dendritic cells (pDCs) contribute to innate antiviral immune responses by producing type I interferons. Although human pDCs can induce T cell responses upon viral infection, it remains unclear if pDCs can present exogenous antigens. Here, we show that human pDCs exploit FcγRII (CD32) to internalize antigen–antibody complexes, resulting in the presentation of exogenous antigen to T cells. pDCs isolated from melanoma patients vaccinated with autologous monocyte-derived peptide- and keyhold limpet hemocyanin (KLH)–loaded dendritic cells, but not from nonvaccinated patients or patients that lack a humoral response against KLH, were able to stimulate KLH-specific T cell proliferation. Interestingly, we observed that internalization of KLH by pDCs depended on the presence of serum from vaccinated patients that developed an anti-KLH antibody response. Anti-CD32 antibodies inhibited antigen uptake and presentation, demonstrating that circulating anti-KLH antibodies binding to CD32 mediate KLH internalization. We conclude that CD32 is an antigen uptake receptor on pDCs and that antigen presentation by pDCs is of particular relevance when circulating antibodies are present. Antigen presentation by pDCs may thus modulate the strength and quality of the secondary phase of an immune response.

The objectives of this study were to investigate the effects of intratumorally (i.t.) administered recombinant human interleukin-12 (rhIL-12) on the distribution and function of B cells in the primary tumors, the locoregional lymph nodes and peripheral blood of head and neck squamous cell carcinoma (HNSCC) patients. The initial characterization of the patients participating in the phase Ib and phase II studies has previously been reported. After rhIL-12 treatment, fewer secondary follicles with a broader outer region of the mantle zones and an increase in interfollicular B-blasts were seen in the enlarged lymph nodes compared with control HNSCC patients. The size of the germinal center (GC) was diminished, partly due to a decrease in the number of CD571 GC cells that have been associated with immune suppression. These changes did not correlate with signs of apoptosis or CXCR5 expression by B cells. Strikingly, in 3 out of 4 IL-12 treated patients, increased IFN-c mRNA expression by B cells was detected. In addition, a highly significant IgG subclass switch was seen in the plasma with more IgG1, less IgG2 and more IgG4, indicating a switch to T helper 1 phenotype. Finally, peritumoral B cell infiltration was a positive prognostic sign for overall survival in the 30 HNSCC patients investigated, irrespective of IL-12 treatment. In conclusion, these data indicate that after i.t. IL-12 treatment in HNSCC, significant activation of the B cell and the B cell compartment occurred and that the presence of tumor infiltrating B cells correlated with overall survival of HNSCC patients. ' 2008 Wiley-Liss, Inc.Key words: interleukin-12; B cell; head and neck squamous cell carcinoma; secondary follicles; germinal center Interleukin-12 (IL-12) is a heterodimeric cytokine that consists of 2 disulfide-linked subunits, i.e., IL-12p40 and IL-12p35.1 IL-12 has a wide range of biological activities 1,2 and has effects on both the innate and adaptive immune system. It stimulates the proliferation and activation of cytotoxic T lymphocytes (Tc) and natural killer (NK) cells and induces the production of cytokines, especially IFN-g.3-5 IL-12 is the key cytokine in the induction of T helper 1 (Th1) responses and thereby of cellular immunity. Furthermore, it inhibits angiogenesis. 6 Because of these abilities, IL-12 was used in preclinical models of antitumor immunotherapy. IL-12 induced regression of established primary tumors, inhibited the formation of tumor metastases and prolonged the survival of tumor-bearing mice.7-10 Several phase I 11-16 and phase II studies in various cancer types [17][18][19][20] have been performed, but only a limited number of clinical responses were observed. In most clinical studies, the immunological effects of IL-12 were studied in peripheral blood. However, after IL-12 administration a transient lymphopenia with a redistribution of activated immune cells from the peripheral blood to the lymph nodes (and primary tumor) occurred. 21 Thus, monitoring of the immune effects of IL-12 therapy solely in the peri...

Serum and salivary concentrations of immunoglobulin A1 (IgA1) and IgA2 were studied in 105 Icelandic children aged 0-12 years. Serum concentrations of both IgA1 and IgA2 increased slightly (P < 0.001) during childhood. The salivary IgA1/IgA2 ratio tended to decrease during the same period; this trend is less apparent when omitting the youngest children. The salivary IgA1 and IgA2 output could be high, even in children with low levels of serum IgA. Only polymeric IgA was found in whole saliva. Interestingly, in serum, most IgA1 and IgA2 were polymeric during infancy. The proportion of polymeric IgA decreased, when the concentration of IgA increased. The polymeric form of IgA might provide the infant with better protection against invading microorganisms by activation of the innate immune mechanisms.