Adaptive immunity/innate immunity

microbiology block 1

Hygiene hypothesis

Immune system evolved because of regular exposure to harmless microbes, parasites, and environmental organisms.

Lymphatic system

sanitation system of the blood. Collection of tissues and organs that collect fluid from the tissues, filter it, and return it to the blood.

Neutrophils

Highly phagocytic. Early responder in fighting many invaders during acute infection, especially bacteria and viruses.

Eosinophils

Moderately phagocytic. Attacks allergens and parasites.

Basophils

attacks allergens and parasites. Releases histamines

Mast cells

moderately phagocytic. Attack bacteria, allergens, and parasites. Reside in tissues and release histamine through degranulation.

Monocytes

highly phagocytic once they mature into macrophages. Activate adaptive immune responses

Dendritic cells

highly phagocytic. Capture and process antigens to present them to T cells to initiate more adaptive immune responses.

Lymphocytes

3 major types. NK cells: innate immunity to viruses, bacteria, parasites, and tumor cells. B & T cells: adaptive immunity.

Cytokines

signaling proteins that are important in controlling growth and activity of other immune system cells and blood cells.

Chemokines

signaling molecules that attract WBCs. Promote inflammation during immune response.

Interleukins

activate innate and adaptive immune responses. Regulates inflammation, influences T cell development.

Interferons

Interfere with viral replication. Also activates innate and adaptive immune responses to other pathogens.

Tumor necrosis factor (TNFs)

Mainly produced by macrophages and regulate immune cells and inflammation.

The classical pathway

complement proteins activated when antibodies bind to a pathogen.

Alternative pathway

complement proteins activated by directly interacting with pathogen.

Lectin pathway

complement proteins activated when mannose binding lectin (MBL) binds to pathogen.

Opsonization

complement protein tags pathogen for phagocytosis

Cytolysis

complement proteins from membrane attack complex (MAC) in pathogen’s plasma membrane. Water and ions rush through MAC and lyse cell.

Inflammation

complement proteins recruit leukocytes releasing signals that cause inflammation.

Antigen

molecule that stimulates an immune response

Immunological memory

rapid immune response during secondary exposure

Cellular response

T cell immunity

Humoral response

B cell immunity

What are MHC molecules?

Cell surface proteins whose job it is to display peptide fragments to T cells.

Do MHC molecules detect pathogens?

they do not recognize pathogens. They present pieces of proteins so T cells can inspect them.

What are MHC genes called in humans?

Human leukocyte antigen (HLA)

MHC I

Surface of all body cells except RBCs. Unique to individuals. Intracellular antigens. Activates CD8 T cells.

MHC II

Surface of antigen presenting cells. Extracellular antigens. Activates CD4 T cells.

What do plasma cells do?

secrete antibodies that bind to specific antigen that triggered immune response.

Where do memory cells reside?

lymphatic tissue

IgG

Most abundant in blood; crosses placenta; secondary response

IgA

Secretions/mucosa — saliva, tears, breast milk, GI/respiratory tract

IgM

First antibody made in a primary response. Early infections. Strong complement activation.

IgE

allergies + parasites, binds mast cells/basophils

IgD

B cell receptor on naive b cells

Epitope

Specific little part of an antigen that an immune receptor recognizes

Clonal expansion

B or T cell makes many copies of itself.

Antibody titer

amount of antibody present in the blood.