Rheumatology

Introduction to the Immune System (The Immune System in Health and Disease) (Rheumatology) Part 1

Definitions •    Adaptive immune system—recently evolved system of immune responses mediated by T and B lymphocytes. Immune responses by these cells are based on specific antigen recognition by clonotypic receptors that are products of genes that rearrange during development and throughout the life of the organism. Additional cells of the adaptive immune system include various […]

Introduction to the Immune System (The Immune System in Health and Disease) (Rheumatology) Part 2

Pattern Recognition Major PRR families of proteins include C-type lectins, leucine-rich proteins, macrophage scavenger receptor proteins, plasma pentraxins, lipid transferases, and inte-grins (Table 1-3).A major group of PRR collagenous glycoproteins with C-type lectin domains are termed collectins and include the serum protein mannose-binding lectin (MBL). MBL and other collectins, as well as two other protein […]

Introduction to the Immune System (The Immune System in Health and Disease) (Rheumatology) Part 3

Dendritic Cells Human dendritic cells (DCs) are heterogenous and contain two subsets, myeloid DCs and plasmacytoid DCs. TABLE 1-7 CC, CXC1, CX3, C1, AND XC FAMILIES OF CHEMOKINES AND CHEMOKINE RECEPTORSa CHEMOKINE RECEPTOR CHEMOKINE LIGANDS CELL TYPES DISEASE CONNECTION CCR1 CCL3 (MIP-1a), CCL5 (RANTES), CCL7 (MCP-3), CCL14 (HCC1) T cells, monocytes, eosinophils, basophils Rheumatoid arthritis, […]

Introduction to the Immune System (The Immune System in Health and Disease) (Rheumatology) Part 4

Neutrophils, Eosinophils, and Basophils Granulocytes are present in nearly all forms of inflammation and are amplifiers and effectors of innate immune responses (Fig. 1-3). Unchecked accumulation and activation of granulocytes can lead to host tissue damage, as seen in neutrophil- and eosinophil-mediated systemic necrotizing vasculitis. Granulocytes are derived from stem cells in bone marrow. Each […]

Introduction to the Immune System (The Immune System in Health and Disease) (Rheumatology) Part 5

Molecular Basis of T Cell Recognition of Antigen The TCR for antigen is a complex of molecules consisting of an antigen-binding heterodimer of either aß or γδ chains noncovalently linked with five CD3 subunits (γ, δ, ε, ζ, and η) (Fig. 1-7). The CD3 ζ chains are either disulfide-linked homodimers (CD3^2) or disulfide-linked heterodimers composed […]

Introduction to the Immune System (The Immune System in Health and Disease) (Rheumatology) Part 6

Cellular Interactions in Regulation of Normal Immune Responses The net result of activation of the humoral (B cell) and cellular (T cell) arms of the adaptive immune system by foreign antigen is the elimination of antigen directly by specific effector T cells or in concert with specific antibody. Figure 1-2 is a simplified schematic diagram […]

Introduction to the Immune System (The Immune System in Health and Disease) (Rheumatology) Part 7

The Cellular and Molecular Control of Programmed Cell Death The process of apoptosis (programmed cell death) plays a crucial role in regulating normal immune responses to antigen. In general, a wide variety of stimuli trigger one of several apoptotic pathways to eliminate microbe-infected cells, eliminate cells with damaged DNA, or eliminate activated immune cells that […]

Introduction to the Immune System (The Immune System in Health and Disease) (Rheumatology) Part 8

Clinical Evaluation of Immune Function Clinical assessment of immunity requires investigation of the four major components of the immune system that participate in host defense and in the pathogenesis of autoimmune diseases: (1) humoral immunity (B cells); (2) cell-mediated immunity (T cells,monocytes); (3) phagocytic cells of the reticuloendothelial system (macrophages), as well as polymorphonuclear leukocytes; […]

The Major Histocompatibility Complex (The Immune System in Health and Disease)(Rheumatology) Part 1

The HLA Complex and Its Products The human major histocompatibility complex (MHC), commonly called the human leukocyte antigen (HLA) complex, is a 4-megabase (Mb) region on chromosome 6 (6p21.3) that is densely packed with expressed genes. The best known of these genes are the HLA class I and class II genes, whose products are critical […]

The Major Histocompatibility Complex (The Immune System in Health and Disease)(Rheumatology) Part 2

Class I Biosynthesis The biosynthesis of the classic MHC class I molecules reflects their role in presenting endogenous peptides. The heavy chain is cotranslationally inserted into the membrane of the endoplasmic reticulum (ER), where it becomes glycosylated and associates sequentially with the chaperone proteins calnexin and ERp57. It then forms a complex with ß2-microglobulin, and […]

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