The adoptive transfer of CD4 1 CD25 1 natural regulatory T cells (Treg) is a promising strategy for the treatment of autoimmune diseases and the prevention of alloresponses after transplantation. Clinical trials exploring this strategy require efficient in vitro expansion of this rare cell population. Protocols developed thus far rely on high-grade purification of Treg prior to culture initiation, a process still hampered by the lack of Treg cell-specific surface markers. Depletion of CD127 1 cells was shown to separate activated conventional T cells from natural Treg cell populations allowing the isolation of highly enriched FOXP3 1 cells with all functional and molecular characteristics of natural Treg. Here, we demonstrate that upon in vitro expansion, CpG methylation in a conserved region within the FOXP3 gene locus increased in CD4 1 CD25 1 CD127 low Treg, correlating with loss of FOXP3 expression and emergence of pro-inflammatory cytokines. Further analysis identified CD45RA À FOXP3 1 memory-type Treg as the main source of converting cells, whereas CD45RA 1 FOXP3 1 Treg from the same donors showed no conversion within 3 wk of in vitro expansion. Thus, Treg cell lineage differentiation does not seem to represent a final fate decision, as natural Treg can lose their cell-type-specific characteristics after repetitive TCR stimulation.Key words: Cellular therapy . Immune regulation . Treg Supporting Information available online Introduction CD4 1 CD25 1 Treg are pivotal for the maintenance of peripheral self-tolerance and imbalances in this T-cell compartment have been shown to contribute to various autoimmune diseases [1]. In murine disease models, adoptively transferred Treg prevent, and in some cases, even cure autoimmunity [2,3]. In addition, they protect from graft rejection after allogeneic organ transplantation [4] as well as from graft-versus-host disease after MHCmismatched stem cell transplantation [5][6][7][8]. Recently, a limited number of Phase I clinical trials exploring the adoptive transfer of Treg have been initiated and several additional trials in various clinical settings are in preparation [9,10]. Prerequisites for the initiation of such trials are (i) the availability of efficient in vitro expansion protocols for this rare cell population and (ii) the ability to unequivocally identify Treg to avoid contamination of 1088Treg cultures with potentially harmful conventional effector T cells (Tconv). While efficient cell culture protocols have recently been established by us and others for the polyclonal as well as antigen-specific Treg cell expansion [11][12][13], the search for an exclusive surface marker for Treg is still ongoing.Contrary to earlier reports, human CD4 1 CD25 high Treg in adult peripheral blood have recently been shown to comprise not only (self-)antigen-experienced, CD45RA À central and effector memory cells, but also a subpopulation of CD45RA 1 naïve recent thymic emigrants [14,15]. We previously demonstrated that these CD45RA 1 CD4 1 CD25 high T cells (RA 1 Treg) homogen...
Multifocal hyperplasia of interstitial cells of Cajal (ICC hyperplasia) is a precursor of hereditary gastrointestinal stromal tumors (GISTs) in patients with germline mutations of c-KIT or PDGFRA, but precursor lesions of sporadic GISTs have not been defined yet. Small hyalinizing stromal tumors of the proximal stomach (referred to in this study as GIST tumorlets) were collected prospectively from 98 consecutive autopsies and additional cases were retrieved from surgical pathology files (total n=57). GIST tumorlets were grossly detectable in 22.5% consecutive autopsies performed in individuals older than 50 years. All lesions were located in the cardia, fundus, or proximal body, and ranged in size from 1 to 10 mm (4 mm). Similar lesions were not detected in the antrum, duodenum, and the remainder of the bowel. Histologically, the spindle cell subtype comprised all cases, with hyalinization and calcification in 57% of cases. The spindle cells were immunohistochemically positive for vimentin, CD117, and CD34. Twenty-four cases yielded sufficient DNA for subsequent molecular analysis, which showed c-KIT mutations in 11 cases (46%) and PDGFRA mutations in 1 case (4%). Sporadic GIST tumorlets of the proximal stomach are common in the general population over the age of 50 years and frequently show somatic c-KIT mutations. GIST tumorlets probably represent the grossly recognizable counterpart of sporadic ICC hyperplasia caused by somatic c-KIT or PDGFRA mutations. Early hyalinization and calcification seems to confer limited growth potential, and complete regression of such lesions is common. GIST tumorlets likely represent preclinical (preneoplastic) lesions that need additional stimuli to evolve into clinical GISTs, raising the possibility of a hyperplasia-neoplasia sequence in the development of sporadic GISTs.
A B S T R A C T PurposePatients with Lynch syndrome are at high risk for colon and endometrial cancer, but also at an elevated risk for other less common cancers. The purpose of this retrospective cohort study was to provide risk estimates for these less common cancers in proven carriers of pathogenic mutations in the mismatch repair (MMR) genes MLH1, MSH2, and MSH6. Patients and MethodsData were pooled from the German and Dutch national Lynch syndrome registries. Seven different cancer types were analyzed: stomach, small bowel, urinary bladder, other urothelial, breast, ovarian, and prostate cancer. Age-, sex-and MMR gene-specific cumulative risks (CRs) were calculated using the Kaplan-Meier method. Sex-specific incidence rates were compared with general population incidence rates by calculating standardized incidence ratios (SIRs). Multivariate Cox regression analysis was used to estimate the impact of sex and mutated gene on cancer risk. ResultsThe cohort comprised 2,118 MMR gene mutation carriers (MLH1, n ϭ 806; MSH2, n ϭ 1,004; MSH6, n ϭ 308). All cancers were significantly more frequent than in the general population. The highest risks were found for male small bowel cancer (SIR, 251; 95% CI, 177 to 346; CR at 70 years, 12.0; 95% CI, 5.7 to 18.2). Breast cancer showed an SIR of 1.9 (95% CI, 1.4 to 2.4) and a CR of 14.4 (95% CI, 9.5 to 19.3). MSH2 mutation carriers had a considerably higher risk of developing urothelial cancer than MLH1 or MSH6 carriers. ConclusionThe sex-and gene-specific differences of less common cancer risks should be taken into account in cancer surveillance and prevention programs for patients with Lynch syndrome.
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