Proteins of Immunology

Immune System

Humoral CellularComplement

Antibody production

Hemopoeisis

Recognizing Self from Non-self: the role of MHC

“Self”,Let’s T killersknow thatI’m supposeto be here.

On APC, provides communicationlink to ImmuneSystem

Lymphocytesinteract to mounthumoral response

Cytokines • Small protein which help activate the different immune

cells, like messengers

• Produced by T cells and Antigen presenting cells (APCs)

• Induce adhesion molecules and increase vascular

permeability

• Attract leukocytes

• Many different types:

– Interleukin-1 (IL-1)

– Interleukin-2 (IL-2)

– Interferon (IFN-)

Kinins

• Cause contraction of muscles distal to site, causing blood to back-up at affected site (swelling)

• Stimulate nerves causing pain• Cause vascular cells to contract and to express

adhesion molecules, allowing cells to attach to capillaries and enter affected site

• Example: bradykinin

Basic immunoglobulin monomer

Typical Ab-Ag interaction has a Kd as low as 10-10 M, Reflecting ionic interactions, H-bonds, hydrophobic, etc.

Immunoglobulins

• IgG

Genes for the immunoglobulins and T-receptors undergo DNA rearrangement.

Light and Heavy chains

The language of Antibody interactions:

Polyclonal antibodies arise from multiple clonesof cells and bind to different parts of antigen withdifferent binding affinities

Monoclonal antibodies arise from a single clone ofcells produced by hybridomas (fusion of B-cell andmyeloma cell), the antibodies are identical

Enzyme-linkedImmunosorbentAssays(ELISA)

Specificity and sensitivity

ELISA and RIA

Western Blots

Two pathways for complement

• Classical pathway – stimulated by antigen-antibody interaction (primarily IgG and IgM)

• Alternative pathway (AP) – stimulated by antigen-antibody interaction (IgA and IgE) OR by non-immunologic means (LPS)

Classical pathway – cascade of proteins

Alternative pathway

Arrow key

• Component cleavage – Red Arrow

• Enzymatic activity – Blue Arrow

• Component assembly – Green Arrow

MAC formation