Immunology Class Switching Flashcards

Study Notes

Class Switching

Lymphocytes differentiate based on maturity and antigen exposure, leading to the production of various immunoglobulins.
Changes from naive lymph (IgM) to lymphoblast, to plasma cell, determine the isotype produced: IgG, IgE, or IgA.
Isotype switching occurs in secondary lymphoid organs (e.g., lymph nodes).
After antigen contact, the variable region remains constant for antigen recognition, while the constant region changes based on the required isotype.

Class Switching in Parasitic Infections

T cells respond to parasitic infections by releasing cytokines that stimulate B cells to produce IgE.

Antibody Manufacturing

Antibodies are synthesized in the rough endoplasmic reticulum (RER), processed in the Golgi apparatus, then secreted.
Immunoglobulins can be embedded in membranes or secreted into blood, depending on their function.

Allotypic Determinants

Genetically encoded features which may lead to immune complications, e.g., maternal antibodies against fetal antigens can cause fetal death.
Variations in antibody types can lead to destruction of Igs, necessitating genetic testing.

Antibody Structure and Functions

Complement activation: IgM and IgG are primary, while IgA plays a minor role.
Opsonization is mainly done by IgG, enhancing macrophage and neutrophil binding.
IgM (minor) and IgA (major) facilitate transport across epithelial barriers.
Key roles include neutralization of viruses (IgG and IgA are major players) and secretion (primarily IgG).

Antigen Binding Sites

Multiple binding sites allow different species to engage antigens in varied manners.
Different B cells can produce varying variable regions through isotypic switching, recognizing multiple antigen parts.

Roles of Antibodies

Key in neutralizing pathogens via tight binding.
Operate as a bridge between pathogens and phagocytic cells, enhancing opsonization.
They recruit phagocytes through specific receptors and stimulate inflammatory responses via IgE.

Resting B Cells vs Plasma Cells

Resting B Cells have surface immunoglobulins and MHC class II, with low growth and no secretion.
Plasma Cells are characterized by a high rate of antibody secretion and active isotype switching.

Antibody-Mediated Effector Functions

Opsonization enhances phagocytosis efficiency through antigen coating.
Neutralization prevents virus binding, and the complement cascade produces C3b.
Antibody-dependent cell-mediated cytotoxicity (ADCC) engages NK cells to recognize and destroy infected cells.
Transcytosis facilitates the movement of antibodies across epithelial membranes (primarily IgA).

Nonclonal Antibodies

Utilized in research and specific therapies by fusing lymphocytes with myeloma cells to create hybrid cells that produce identical antibodies.
These clones are used for studying diseases and understanding immune responses.

Description

Explore the concept of class switching in immunology through these flashcards. Understand how lymphocytes change their immunoglobulin production based on maturity and antigen exposure. This topic is crucial for grasping antibody diversity and immune response.