ib 202 immune system- chapter B

Lymphatic System

-network of organs, vessels, and tissues that work together to move lymph back to circulatory system

-protects from infection and destroys old or abnormal cells

Lymphocytes: B Cells

-B cell originate and mature in bone marrow

-activate in spleen and lymph nodes

transport in circulatory and lymphatic systems

Antibodies and B-cell receptors

-recognize and bind to antigens

-each B cell can synthesize only one kind of antibody (specific to particular antigen)

-adaptive

-inserted in plasma membrane then antibodies release into blood

B-cell Receptors Protein Components

-2 identical light chains, smaller peptides

-variable and constant regions

-2 heavy chains that have transmembrane domain anchoring protein in plasma membrane to B cell

-thousands of copies of B-cell receptors on each B cell

Epitope

-immunoglobins (antibodies, BCRs) don’t bind to entire antigen, bind to epitope (region of antigen)

Hemagglutinin

-antigen on influenza virus with multiple distinct epitopes

-TCRs bind to epitopes

Immunoglobulins

-BCRs and antibodies

-has 5 classes

Lymphocytes: Mature T Cells

-recognize and kill host cells that are infected with virus

-leave the thymus and travel to secondary lymphoid tissues

Lymphocytes: T-Cell Precursors

-travel from the bone marrow to develop in the thymus

Lymphocyte: T Cell Location

originate in bone marrow

matures in thymus

activates in spleen and lymph nodes

transports in circulatory and lymphatic systems

TCRs (T-cell Receptors)

-can’t bind antigens on their own

-TCR recognizes antigens through antigen presentation

TCR components

-2 protein chains

• alpha and beta chain

• transmembrane domain

• similar to shape of 1 “arms” in antibody of BCR

Lymphoma Cancer

-begins in lymphocytes (T or B cells)

-abnormal lymphocytes build up in lymph nodes

Hodgkin Lymphoma

-abnormal lymphocytes usually from B cells

Non-Hodgkin Lymphoma

-large group of cancers starting in lymphocytes

-cancers from B or T cells

Psoriasis

-autoimmune disease with abnormal growth of skin cells

-pathogens, trauma, stress, DCs and macrophages release pro-inflammatory cytokines

Psoriasis Steps

1) cytokines can activate dermal T cells and cytokine producing cells to secrete abundant cytokines to promote adaptive immune response

-IL factors induce keratinocyte hyperproliferation which release chemokines and attract more immune cells to skin

2) positive feedback loop leads to psoriatic lesions