A course on Basic Immunology,with emphasis on immunologic diseases and

therapeutic strategies

Abul K. Abbas, Hidde Ploegh and Caetano Reis e Sousa

Course schedule

• 9:00. Overview Abul Abbas

• 9:15. Innate immunity Caetano Reis e Sousa

• 10:15. Coffee break

• 10:30. Antigen presentation Hidde Ploegh

• 11:30. T cell activation Abul Abbas

• 12:30. Lunch

• 2:00. T cell subsets Abul Abbas

• 3:00. B cells Hidde Ploegh

• 3:45. Break

• 4:00. Tolerance and autoimmunity Abul Abbas

Themes of the course

• Introduction to the nomenclature ofimmunology

• Basic principles: mechanisms underlyingimmune responses

• Emerging concepts, and their potentialclinical and therapeutic implications

• Defense against infections

• Defense against some tumors

• Barrier to transplantation, gene therapy

• Cause of disease (“immune-mediatedinflammatory diseases”)

What does the immune system do?

Innate immunity: always present (ready to attack); many pathogenic microbes have evolved to resist innate immunityAdaptive immunity: stimulated by exposure to microbe; more potent

Cells of the immune system

• Lymphocytes: the cells of adaptive immunity;recognize antigens and develop (differentiate)into cells that perform the defense functions

• Antigen-presenting cells: cells that captureantigens and display them to lymphocytes

• Effector cells: leukocytes (white blood cells)that eliminate microbes (the “effect” of theimmune response); may be lymphocytes, butare often other leukocytes

Capture and presentation of antigens

Dendritic cellsare specializedantigen-presentingcells (APCs) thatpick up and displayproteins forrecognition byT lymphocytes.

Antigens aretransported tolymphoid organs(e.g. lymph nodes)where adaptiveimmune responsesare initiated

Classes of lymphocytes

Helper T cells are master controllers of immune responses The CD nomenclature for lymphocytes and other cells

The humoral immune response: activation ofB lymphocytes and production of antibody

Rapid proliferation of antigen-specific lymphocytes (keeps pace with replicating microbes), e.g. 1 B cell --> 4,000 Ab-secreting cells --> >1012 antibody molecules/day Differentiation: generation of Ab secreting cells

Cell-mediated immunity: T cell activation

Activation of CD8+ T cells follows a similar sequence

Cytokines

• Secreted proteins that mediate immune andinflammatory reactions, and communicationsamong leukocytes and other cells(“interleukins”)

• Actions of a cytokine are most oftenautocrine (on cell that produces it) andparacrine (on neighbors), rarely endocrine(distant)

A summary of adaptive immune responses

The immune system can cause disease

• Normal immune responses are induced byand defend us against infectiouspathogens

• Immune responses can be inappropriatelyinduced and may cause injury to normaltissues, resulting in disease– The mechanisms of tissue injury are the

same as the mechanisms that eliminatemicrobes