Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019621 (Langerhans cell histiocytosis)
 3,250 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The proliferating cell in histiocytosis X has been thought to be an abnormal Langerhans cell since the identification in 1965 of the characteristic X-bodies morphologically identical to the Birbeck granules of epidermal Langerhans cells. This conclusion is based primarily on this finding and on morphologic similarities at the light microscopic level. Enzyme histochemical data have been somewhat conflicting and have not provided strong support for this conclusion. Recently, immunohistochemical studies have shown data consistent with a Langerhans cell origin for histiocytosis X cells. This study documents the presence of nonspecific esterase, acid phosphatase, and adenosine triphosphatase in both Langerhans cells and histiocytosis X cells. Both types of cells also react with antibodies directed against widely distributed leukocyte antigens (HLA-A,B,C; Ia; L3B12); Langerhans cell/thymocyte antigen [Leu 6(T6)]; histiocyte antigen (Leu-M3); helper T-cell/histiocyte antigen [Leu-3(T4)]; and S-100 protein. These results complement earlier immunologic studies and add enzyme histochemical data that strongly support the concept of histiocytosis X as a proliferative disorder of cells of Langerhans lineage.
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PMID:Histiocytosis X cells and Langerhans cells: enzyme histochemical and immunologic similarities. 638 Dec 83

Langerhans cell histiocytosis is a rare disease with an unknown etiology and poorly understood pathogenesis. Immunologic, viral, and proliferative clonality causes have all been considered. To determine whether Langerhans cell histiocytosis and its two main subgroups, single-system and multisystem disease, are associated with HLA-A, -B, -Cw, or -DR alleles, a total of 84 patients <15 y of age at the time of diagnosis and of Nordic origin were analyzed, 82 for HLA class I and 76 for HLA class II. Stratification of the patients into two subgroups, single-system disease (skin only, and monostotic and polyostotic disease) and multisystem disease with or without organ dysfunction, showed that patients with single-system disease (17 of 45, 38%) more often (p = 0.00018 and, after correction, p = 0.029) had the phenotype HLA-DRB1*03 compared with patients with multisystem disease (1 of 31, 3%). In the patients with multisystem disease a nonsignificant reduction of the frequency of this phenotype was seen compared with controls (p = 0.02, uncorrected). In 14 of the patients with single-system disease, but none with multisystem disease, the deduced haplotype HLA-A*01, B*08, DRB1*03 was found. High-resolution typing, performed in nine patients, revealed that all had the HLA-A*0101, B*0801, DRB1*0301, DQB1*0201 alleles. Our findings suggest an immunogenetic heterogeneity in the two clinical entities of Langerhans cell histiocytosis and indicate that HLA-DRB1*03 may play a protective role against developing multisystem disease. Further studies to confirm these findings are desired.
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PMID:Immunogenetic heterogeneity in single-system and multisystem langerhans cell histiocytosis. 1270 Mar 69

Langerhans Cell Histiocytosis (LCH) is a neoplastic disorder of hematopoietic origin characterized by inflammatory lesions containing clonal histiocytes (LCH-cells) intermixed with various immune cells, including T cells. In 50-60% of LCH-patients, the somatic BRAF V600E driver mutation, which is common in many cancers, is detected in these LCH-cells in an otherwise quiet genomic landscape. Non-synonymous mutations like BRAF V600E can be a source of neoantigens capable of eliciting effective antitumor CD8+ T cell responses. This requires neopeptides to be stably presented by Human Leukocyte Antigen (HLA) class I molecules and sufficient numbers of CD8+ T cells at tumor sites. Here, we demonstrate substantial heterogeneity in CD8+ T cell density in n = 101 LCH-lesions, with BRAF V600E mutated lesions displaying significantly lower CD8+ T cell:CD1a+ LCH-cell ratios (p = 0.01) than BRAF wildtype lesions. Because LCH-lesional CD8+ T cell density had no significant impact on event-free survival, we investigated whether the intracellularly expressed BRAF V600E protein is degraded into neopeptides that are naturally processed and presented by cell surface HLA class I molecules. Epitope prediction tools revealed a single HLA class I binding BRAF V600E derived neopeptide (KIGDFGLATEK), which indeed displayed strong to intermediate binding capacity to HLA-A*03:01 and HLA-A*11:01 in an in vitro peptide-HLA binding assay. Mass spectrometry-based targeted peptidomics was used to investigate the presence of this neopeptide in HLA class I presented peptides isolated from several BRAF V600E expressing cell lines with various HLA genotypes. While the HLA-A*02:01 binding BRAF wildtype peptide KIGDFGLATV was traced in peptides isolated from all five cell lines expressing this HLA subtype, KIGDFGLATEK was not detected in the HLA class I peptidomes of two distinct BRAF V600E transduced cell lines with confirmed expression of HLA-A*03:01 or HLA-A*11:01. These data indicate that the in silico predicted HLA class I binding and proteasome-generated neopeptides derived from the BRAF V600E protein are not presented by HLA class I molecules. Given that the BRAF V600E mutation is highly prevalent in chemotherapy refractory LCH-patients who may qualify for immunotherapy, this study therefore questions the efficacy of immune checkpoint inhibitor therapy in LCH.
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PMID:Apparent Lack of BRAF V600E Derived HLA Class I Presented Neoantigens Hampers Neoplastic Cell Targeting by CD8+ T Cells in Langerhans Cell Histiocytosis. 3199 17