2. Introduction/Terminology
Immunology: the study of the body's defense against infection
Immunity: Resistance to disease
Immune system: The collection of cells, tissues and molecules that mediate the resistance
Immune response: The coordinated work of the immune system to defend the host against foreign substances.
Innate immunity: The native or natural immunity.
Adaptive immunity: Acquired as an adaptation to infection

3. Antigen: Any molecule that can bind to an Ab (microbes, drugs, pollen …….) OR any molecule that can produce adaptive immunity
Antigen determinant (epitope): a portion of an antigen that is bound to a given Ab or antigen receptor.
Antigen presentation: Process of displaying the antigen as a peptide fragment on the surface of the cell.
Adjuvant: Killed bacteria or bacterial extracts used to assess the non-immunogenic antigen to induce an immune response

4. Immunity
The term immunity is derived from the Latin word immunitas, which referred to the protection from legal prosecution offered to the Roman senators during their tenures in office.
Defined by: all mechanisms used by the body as protection against environmental agents that are foreign to the body.

5. Immunity
These foreign agents may be microorganisms or their products, foods, chemicals, drugs, pollen, or animal hair and dander.
Immunity may be innate or acquired.
adaptive
Innate

6. Features of Innate and Adaptive immunity
Characteristics
Innate
Adaptive
Specificity
Microbes and products of damaged host cells
Microbial and non microbial antigens
Diversity
Limited; germline encoded
Very large; receptors are produced by somatic recombination of gene segments
Memory
None
yes
Non-reactivity to self
Yes
Components
Cellular and chemical barriers
Skin, mucosal epithelia; antimicrobial molecules
Lymphocytes in epithelia; antibodies secreted at epithelial surfaces.
Blood Proteins
Complements, others
Antibodies
Cells
Phagocytes, natural killer cells
Lymphocytes

7. The Kinetics of the innate and adaptive immune responses are approximation and may vary in different infections.

8. Acquired immunity is induced by immunization, which can be achieved in several ways:
Active immunization:
It refers to immunization of an individual by administration of an antigen.
2. Passive:
It refers to immunization through the transfer of specific antibody from an immunized individual to a nonimmunized individual.
3. Adoptive immunization:
It refers to the transfer of immunity by the transfer of immune cells.

9. Cells Involved in the Acquired Immune Response:
There are three major cell types involved in acquired immunity and that complex interactions among these cell types are required for the expression of the full range of immune responses.
T cells
B cells
Both exhibit specificity toward an antigen.
The major recognition and reaction functions of the immune response are contained within the lymphocytes.

10. 3. Antigen – presenting cells “APCs”
Such as Macrophages and dendritic cells.
They do not have antigen – specific receptors as do the lymphocytes.
Their function is to process and present antigen to the specific receptors “T cell receptors” on T lymphocytes.
Two types of special molecules that function in antigen presentation are present on the surface of APCs: