MHC and Antigen Presentation to Lymphocyte PDF

MHC and Antigen presentation to lymphocyte Immunology Dep., School of Medicine, Shahid Beheshti University of Medical Sciences  MHC (Major Histocompatibility Complex) (MHC) George snell  ‫ایمنی هومورال‬ ‫ایمنی سلولی‬ ‫میکر...

MHC and Antigen presentation to lymphocyte Immunology Dep., School of Medicine, Shahid Beheshti University of Medical Sciences  MHC (Major Histocompatibility Complex) (MHC) George snell  ‫ایمنی هومورال‬ ‫ایمنی سلولی‬ ‫میکروب های‬ ‫میکروب های‬ ‫میکروب های‬ ‫خارج سلولی‬ ‫درون‬ ‫فاگوسیتوز شده‬ ‫درون ماکروفاژها‬ ‫سیتوپالسمی‬ ‫سلول‬ ‫پاسخ دهنده‬ ‫‪B‬لنفوسیت‬ ‫‪T‬لنفوسیت‬ ‫‪CD4‬با مولكول سطحي‬ ‫‪T‬لنفوسیت‬ ‫‪CD8‬با مولكول سطحي‬ ‫روش انتقال‬ ‫سرم‬ ‫خنثی و‬ ‫فعال شدن ماکروفاژ‬ ‫کشتن سلول آلوده‬ ‫عملکرد نهایی‬ ‫محدود کردن‬ ‫برای کشتن میکروب‬ ‫و حذف‬ ‫ذرات خارج سلولی‬ ‫فاگوسیتوز شده‬ ‫مخزن عفونت‬ Antigen recognition by T-lymphocytes T cell B cell Properties of Major Histocompatibility Complex (MHC) Genes  The two types of polymorphic MHC genes, namely, the class I and class II MHC genes,  MHC genes are the most polymorphic genes present in the genome.  MHC genes are codominantly expressed in each individual. MHC (locus, genes and alleles) Figure 3-23  MHC genes are codominantly expressed in each individual.  Properties of MHC proteins Peptide binding sites of MHC molecules MHC molecule binding sites Can bind many different amino acid sequences Length of peptides bound MHC class I 8 – 10 amino acids MHC class II 13 – 25 amino acids  ‫‪ CD8‬با مولكول سطحي ‪T‬لنفوسیت‬ ‫آنتی ژن‬ ‫پپتیدي‬ ‫‪APC‬‬  ‫‪ CD4‬با مولكول سطحي ‪T‬لنفوسیت‬ ‫) ‪ helper‬كمكي یا ‪(T‬لنفوسیت‬ ‫آنتی ژن‬ ‫پپتیدي‬ ‫‪APC‬‬ Antigen processing and presenting to T lymphocyte Properties of antigen recognized by T lymphocytes  Most T lymphocytes recognize only peptides  T cells are specific for amino acid sequences of peptides. Properties of antigen recognized by T lymphocytes  T cells recognize and respond to foreign peptide antigens only when the antigens are attached to the surfaces of APCs.  T cells from anyone individual recognize foreign peptide antigens only when these peptides are bound to and displayed by the MHC molecules of that individual.  Properties of antigen recognized by T lymphocytes  CD4" helper T cells recognize peptides bound to class II MHC molecules  Whereas CD8+T cells recognize peptides bound to class I MHC molecules CD1 Pathway for lipid structures presentation to T cell.  Properties of antigen recognized by T lymphocytes  CD4+ class II MHC -restricted T cells recognize peptides derived mainly from extracellular proteins that are internalized into the vesicles of APCs,  Whereas CD8+T cells recognize peptides derived from cytosolie, usually endogenously synthesized proteins. Antigen presenting cells (APCs) properties Antigen capture (mannos receptor, CR, sIg) Co- expression of class I and class II MHC  Expression of wide panel of TLRs Antigen presenting cells (APCs), which capture and display the antigens to T cells DC (Initiating naive T Cell Responses ) B & MQ (Effector phase of T Cell Responses)  Vascular endothelial cells  epithelial and mesenchymal cells Antigen presenting cells (APCs) functions Associations of HLA alleles with increased risk for various diseases