Eosinophils: Characteristics and Functions

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Questions and Answers

Which CD molecule is responsible for supporting the T-cell receptor (TCR) and transducing signaling when engaged?

CD8

CD3 (correct)

CD19

CD4

Which CD molecule is primarily found on helper T-cells and is important for recognizing antigens presented by MHC class II molecules?

CD4 (correct)

CD20

CD28

CD8

What is the main site of maturation for B lymphocytes in several mammalian species, including humans and mice?

Spleen

Lymph node

Thymus

Bone marrow (correct)

Which method is NOT used to classify lymphocytes?

By the type of MHC molecules they express Signup and view all the answers

Which size range is INCORRECTly matched with lymphocyte morphology?

Small: 7 to 10 µm Signup and view all the answers

Which type of lymphocyte is primarily involved in the adaptive immune response?

T cells Signup and view all the answers

Which type of cells have MHC Class II markers?

B lymphocytes, T lymphocytes, macrophages Signup and view all the answers

Why are cells without the specific MHC markers classified as non-self?

Because they carry foreign molecules Signup and view all the answers

In terms of immune system recognition, what happens to cells marked as 'self'?

They are recognized as part of the body Signup and view all the answers

What is the main function of MHC Class I markers?

Identification of self-cells Signup and view all the answers

How are non-self cells perceived by the immune system?

As foreign because they lack specific MHC markers Signup and view all the answers

Which statement accurately describes the role of receptors in immune responses?

The engagement of receptors provides a wide range of responses based on cell type and ligands Signup and view all the answers

What is the main role of eosinophils in the immune system?

Fight parasitic infections Signup and view all the answers

Which cells express HLA class II proteins on their surface?

Macrophages Signup and view all the answers

What distinguishes HLA class I from HLA class II molecules?

Expressed on nucleated cells vs. antigen presenting cells Signup and view all the answers

What is the significance of the MHC genes polymorphism?

Tissue rejection in transplant patients Signup and view all the answers

Which immune response does the HLA system play a major role in?

Adaptive immune response Signup and view all the answers

Study Notes

Cluster of Differentiation Molecules

Cluster of differentiation (CD) molecules are found on the surfaces of many cell types and serve as indicators of the functional capacities of leukocytes and other cells.
Over 350 CD molecules have been identified.

CD Molecules in Adaptive Immunity

Three major CD molecules are important in adaptive immunity: CD3, CD4, and CD8.
CD3 supports the T-cell receptor (TCR) and transduces trans-membrane signaling when the TCR is engaged.

Lymphocytes

Lymphocytes are the major cells of the adaptive immune system.
They can be classified according to three general methods: type of receptors involved, place of basic training, and type of expression of membrane molecules (CD).
Lymphocytes range in size from small (4-7 µm) to large (11-15 µm).

B Lymphocytes (B Cells)

B lymphocytes derive their name from bone marrow, their major site of maturation.
They can be distinguished by their expression of membrane molecules known as cluster of differentiation (CD).

Eosinophils

Eosinophils have "eosin-living" granules and are bilobed granulocytes with cytoplasmic granules that contain basic proteins.
They are an active component in both innate and adaptive immune responses to parasitic infections.

Major Histocompatibility Molecules (MHC)

MHC molecules are also known as the human leukocyte antigen (HLA) complex.
They are a segment of chromosome 6 containing several genes that encode enzymes and structural molecules needed for the activation and function of B and T cells.
MHC molecules play a major role in considering a transplant tissue as foreign or not (histocompatibility).

HLA Molecules

HLA class I molecules are expressed on the surface of almost all nucleated cells.
They consist of a large polypeptide (α-polypeptide) and a small polypeptide (β2-microglobulin).
HLA class I molecules can bind to short antigenic peptides in their groove.
HLA class II molecules are expressed on the surface of antigen-presenting cells (macrophages, dendritic cells, and B cells).
They consist of two large polypeptides (α and β polypeptides).

Distinguishing between Self and Non-Self

The immune system coexists with every cell in the body, which are identified as 'self' and marked with protein markers coded by the major histocompatibility complex (MHC) genes.
Any cell that does not display the specific MHC marker is treated as an antigen.

MHC Proteins

MHC Class I proteins are found on all body cells that have a nucleus.
MHC Class II proteins are found only on B and T lymphocytes and macrophages.
Both markers contribute to the specific identity of the cell.

Receptors in the Immune System

Receptors are important for the function of the immune system.
Engagement of receptors provides a wide range of responses depending on the type of cell or molecule associated with the receptor and the type of receptor and ligand.

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Description

Learn about the characteristics and functions of eosinophils, a type of white blood cell involved in immune responses to parasitic infections. Discover the role of eosinophils in both innate and adaptive immunity, as well as their unique cytoplasmic granules containing basic proteins.