Lecture 31: Dealing With Pathogens

Non-specific immunity: Defends against a wide variety of pathogens. Gross anatomical level or molecular level

Pathogen Associated Molecular Patterns (PAMPs)

Specific immunity targets a particular disease strain

Innate Immunity: dominant form

Adaptive Immunity: Found only in vertebrates and is specific

Involves antibodies & T cells, rearrangement of DNA

Anatomical defenses in innate immunity:

Exoskeleton in Insects

Vertebrate skin

Plant Epidermis

Pattern Recognition Receptors (PRRs) found in plants, fungi, animals bind to PAMPs

“Toll-like receptors” (TLRs) are found in animals and in fungi

Recognize PAMPs

Blood, lymph, & immunity in vertebrates (Specific)

Blood cells are produced in the bone marrow; white blood cells of various types play key roles in both nonspecific and specific immunity

Lymph: Fluid derived from blood and other tissues. From tissues, lymph moves into lymph system vessels

Lymph vessels join and eventually form the thoracic duct, which joins the circulatory system at a major vein near the heart

Lymphocytes: involved in removing invaders from lymph in nodes and staging specific immune response

Nonspecific Immunity:

Phagocytes- white blood cells, travel freely

Inflammation is a response to injury.

Mast cells are cells adhering to skin and organ linings; release chemical signals:

Prostaglandins—dilate blood vessels and interact with nerve endings, responsible for pain

Histamine—amino acid derivative that leads to itching and allergic reactions

Four Key Features

Discrimination of self from non-self

Diversity

Specificity

Immunological memory

Antibodies belong to a group of proteins called immunoglobulins

Antibody diversity is generated by random rearrangement of genomic sequences in differentiating B cells.

Class switching- exchanging C regions- can occur after exposure to antigen