Immune system

Adaptive immunity – B cell

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INTRODUCTION

What is the Immune system The immune system is the body's defense

against infectious organisms and other invaders. Through a series of steps called the immune response, the immune system attacks organisms and substances that invade our systems and cause disease. The immune system is made up of a network of cells, tissues, and organs that work together to protect the body.

Immune system

Innate immunity

· Responses are Broad-Spectrum (non-specific)

· There is no memory or lasting protective immunity

· There is a limited repertoire of recognition molecules

· The responses are phylogenetically ancient

Immune system

Adaptive immunity · Specific immunity · Humoral immune response (B cell) · cell mediated immune response (T cell) · This makes the information about the antibody at the memory cell and put.

The adaptive immune system

The two main classes of adative immune responses.

Lymphocytes carry out both classes of responses. Here, the lymphocytes are responding to viral infection. In one class of response,

B cell secrete antibodies that neutralize the virus. In the other, a cell-mediated response, T cell kill the virus –infected cell

B cell

B Cell induces Ag-Ab reactionPlasma cell

·An antibody manufacture (IgG, IgA, IgM, IgE, IgD) ·Golgi complex is develop

because the secretion activity is active.Memory cell

·After termination of immune response, the cell memories the Ag.

·When reinvaded by the same Ag, Immune response is more short.

Antibody structure

Antibodies are immune system related proteinscalled immunoglobulins. Each antibody consists of four polypeptides–Two heavy chains and two light chains joined to form a "Y" shaped molecule.

variable region, composed of 110-130 amino acids, give the antibody its specificity for binding antigen. Treating the antibody with a protease can cleave this region, producing Fab or fragment antigen binding that include the variable ends of an antibody. Material used for the studies shown below originatedfrom Fab.

The constant region determines the mechanism used to destroy antigen. Antibodies are divided into five major classes, IgM, IgG, Iga, IgD and IgE, based on their constant region structure and immune function.

Kinds of the Antibody

IgG Inherited through the placenta. IgM Produced at first stage of the immunity reaction. participate in the immunity reaction about a compositeness antigen infection.IgA protect the mucous membrane surface.IgD The role of an antigen promotion lymph differentiation.IgE Relevance to an allergy disease.

B cell development

All of the stages shown occur independently of antigen. When theyare activated by their specific foreign antigen and helper T cell inperipheral lymphoid organs, mature naïve B cell proliferate and diff-erentiate and differentiate into effector or memory cell.

B cell activation

When naïve or memory B cells are activation by antigen (and helper T cells), they proliferate and differentiate into effector cells. The effector cells produce and secrete antibodies with a unique antigen-binding site, which is the same as that oftheir original membrane-bound antibodies that served as antigen receptors.

Anergy: two signal theory of B cell activation

Early theories of B cell activationproposed that two signals were required and that lacking one, cells would become "paralyzed.“Self-reactive cells would be deleted because of the low probability of two such faulty signals being generated simultaneously. It is now known that mature B cells that have received their first signal rapidly die unless they receive their second signal. The strength of the signal also affects time to death, withstrong signals inducing rapid apoptosis in B cells.

B cell activation & effector

Antigen Recognition

effect of T cell & cytokine

B cell activation

Continued activating or processing of apoptosis

Summary