The programmed cell death-1 receptor (PD-1) is an immune checkpoint inhibitor which is expressed on the surface of immune effector cells. It is activated mainly by PD-L1 which can be expressed by all human cells. The PD-1/PD-L1 pathway plays a subtle role in maintaining peripheral T-lymphocyte tolerance and regulating inflammation. In cancer, the expression of PD-L1 seems to be one of the major immune escape mechanisms. Many studies have shown efficacy of blocking PD-1 or PD-L1 with specific antibodies like pembrolizumab or atezulizumab. In breast cancer, potential response was demonstrated in metastatic triple-negative breast cancers.

The antibacterial peptide SA-FF22, produced by the pathogen Streptococcus pyogenes strain FF22 was purified and features of its primary and secondary structure were characterised. Mass spectrometry demonstrated the pure peptide had a mass of 2794Da while, amino acid analysis revealed the presence of the unusual, thioether amino acids lanthionine and 3-methyllanthionine ; thus SA-FF22 is a member of the group of antibacterial polypeptides termed lantibiotics. Furthermore, amino acid sequencing showed a unique sequence which was blocked at position 23 by a residue of the unsaturated amino acid 2,3-didehydrobutyrine. Carboxypeptidase-Y digestion could be used to demonstrate that serine occupies the C-terminal position only after complete oxidation of the thioether amino acid bridges, suggesting that the three-dimensional structure of the native peptide may prevent access of the enzyme to the C-terminus. Fragmentation of the native peptide with a variety of proteolytic enzymes failed to yield a peptide containing less than all three of the cross-linked lanthionine and methyllanthionine residues and demonstrated that all three thioether bridges overlapped. Analysis of the circular dichroism of SA-FF22 in various concentrations of 2,2,2-trifluoroethanol in water, SDS micelles and in the presence of artificial phospholipid vesicles suggested that there is significant change in its secondary structure from aqueous to lipophilic environments.SA-FF22 is a bacteriocin-like inhibitory substance produced by Streptococcus pyogenes strain FF22 and which has been shown to be bactericidal for many strains of related streptococci [l]. Subsequent to its discovery, SA-FF22 was partially purified and characterised [2, 31. In these initial studies it was demonstrated that the inhibitory factor contained an essential proteinaceous component since it was inactivated by several proteolytic enzymes, was of approximately 8000Da as determined by dialysis and gel filtration, was stable in acid solution and at high temperatures but was not stable under alkaline conditions and was active against only certain Gram-positive bacteria. Further studies showed that the genetic determinant(s) that controlled SA-FF22 production appeared to be lost spontaneously in aged cultures or through the use of plasmid 'curing' agents, suggesting that SA-FF22 production was encoded on a plasmid. AdditionCorrespondence to R. W. Jack,

No abstract

The gene encoding monophosphatidylinositol inositol phosphohydrolase (PI-specific phospholipase C, PI-PLC) of Bacillus thuringiensis was cloned in Staphylococcus carnosus TM300. The complete coding region comprises 987 base pairs corresponding to a precursor protein of 329 amino acids (molecular weight, 38,095). The NH2-terminal sequence of the purified enzyme from Escherichia coli indicated that the mature PI-PLC consists of 299 amino acid residues with a molecular weight of 34,586. Polyacrylamide gel electrophoresis revealed the same molecular weight for the purified enzyme isolated from the DNA-donor strain of B. thuringiensis and from the E. coli clone. By computer analysis, the secondary structure was predicted. The enzyme from the E. coli recombinant shows no activity on other phospholipids and sphingomyelin. The cleaving specificity of PI-PLC was examined by thin layer chromatography.

The specificity of peptide binding to MHC molecules is defined by binding motifs composed of several relatively conserved anchor positions. The peptide binding motifs of murine MHC class II I-A molecules are functionally important but poorly characterized. Here we use peptide binding studies and isolation of naturally presented peptides to characterize the peptide binding motif of the MHC class II I-A molecule, RT1.BI, a molecule that is involved in experimental autoimmunity in the Lewis rat. We now report that, similar to other class II motifs, the RT1.BI motif consists of a nonamer sequence with four major anchor positions (P1, P4, P6 and P9). Residues at P4 and P9, rather than at P1, appeared to be particularly important for binding. Negatively charged residues were favored at P9, consistent with the presence of a serine at position 57 of the RT1.BI beta chain. This RT1.BI motif could be observed in the dominant autoantigenic T cell epitopes mapped previously in the Lewis rat. These results highlight a general similarity and some important differences in the organization of MHC class II peptide binding motifs. The reported RT1.BI motif should facilitate the prediction and design of T cell epitopes for the induction and control of experimental autoimmune diseases in Lewis rat models.

Intact and aCTC are predictive of outcome in MBC. Apoptotic CTC counts ≥ 5/7.5 ml in conjunction with iCTC at baseline have an independent unfavorable prognostic impact on OS. Decreasing aCTC at ≥ 5/7.5 ml in serial enumeration is associated with favorable outcome. Therefore, separate enumeration of iCTC and aCTC is useful in tailoring systemic treatment.

cent transformed cells or inhibiting their outgrowth. This antitumor immunity is substantiated by the main cellular effectors of the innate and the adaptive immune system, namely natural killer cells, natural killer T cells, and T cells (TCs), as well as increased proimmune humoral factors (e.g., interferons) in the tumor microenvironment. On the other hand, in the tumor-promoting phase referred to as 'immune escape', the immune system can further tumor progression either by selecting cancer cells that are more capable of surviving the host's immunocompetence or by modifying the tumor microenvironment in such a way that tumor outgrowth is facilitated [2]. In between the above phases is the equilibrium where cancerous cells are kept under control but are not eliminated by the immune system. This balance of antitumor and tumor-promoting factors may maintain the tumor in a functionally inactive state of dormancy over a period of many years [3].The processes mentioned above also make up the rationale for the development of immunotherapeutic options in breast cancer (BC) [3][4][5], as characteristically in this tumor entity, already at very early stages, cancer cells are able to disseminate hematogenously from the primary tumor site, and distant metastases often occur only after many years of latency [6]. In this context, one predominant organ associated with the dissemination and survival of BC tumor cells is, besides others such as locoregional lymph nodes, the bone marrow (BM). Of note, the detection of disseminated BM tumor cells correlates with an increased rate of secondary osseous and visceral metastases and with a worse overall survival [7][8][9][10][11].Consequently, in addition to surgical resection of the primary tumor and locoregional irradiation, curative BC therapy aims at eliminating disseminated micrometastatic tumor cells. In this context, besides cytostatic and/or hormonal therapies, new supportive treatment options like immunotherapy are increasingly gaining oncological interest. Hence, we also review aspects of BC immunoediting processes with respect to potential immunotherapeutic approaches. KeywordsBreast cancer · Cellular immunity · Immune escape · Immunoediting · Immunosurveillance · Immunotherapy Summary More recently, immunotherapy has emerged as a novel potentially effective therapeutic option also for solid malignancies such as breast cancer (BC). Relevant approaches, however, are determined by the 2 main elements of cancer immunoediting -the elimination of nascent transformed cells by immunosurveillance on the one hand and tumor immune escape on the other hand. Correspondingly, we here review the role of the various cellular immune players within the host-protective system and dissect the mechanisms of immune evasion leading to tumor progression. If the immune balance of disseminated BC cell dormancy (equilibrium phase) is lost, distant metastatic relapse may occur. The relevant cellular antitumor responses and translational immunotherapeutic options will also be discussed in terms of cli...

Despite multidisciplinary local and systemic therapeutic approaches, the prognosis for most patients with brain metastases is still dismal. The role of adaptive and innate anti-tumor response including the Human Leukocyte Antigen (HLA) machinery of antigen presentation is still unclear. We present data on the HLA class II-chaperone molecule CD74 in brain metastases and its impact on the HLA peptidome complexity.We analyzed CD74 and HLA class II expression on tumor cells in a subset of 236 human brain metastases, primary tumors and peripheral metastases of different entities in association with clinical data including overall survival. Additionally, we assessed whole DNA methylome profiles including CD74 promoter methylation and differential methylation in 21 brain metastases. We analyzed the effects of a siRNA mediated CD74 knockdown on HLA-expression and HLA peptidome composition in a brain metastatic melanoma cell line.We observed that CD74 expression on tumor cells is a strong positive prognostic marker in brain metastasis patients and positively associated with tumor-infiltrating T-lymphocytes (TILs). Whole DNA methylome analysis suggested that CD74 tumor cell expression might be regulated epigenetically via CD74 promoter methylation. CD74high and TILhigh tumors displayed a differential DNA methylation pattern with highest enrichment scores for antigen processing and presentation. Furthermore, CD74 knockdown in vitro lead to a reduction of HLA class II peptidome complexity, while HLA class I peptidome remained unaffected.In summary, our results demonstrate that a functional HLA class II processing machinery in brain metastatic tumor cells, reflected by a high expression of CD74 and a complex tumor cell HLA peptidome, seems to be crucial for better patient prognosis.Electronic supplementary materialThe online version of this article (10.1186/s40478-018-0521-5) contains supplementary material, which is available to authorized users.