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Specific Immune Defenses

I). Definitions:

A). Antigen:

A substance or part of a substance that activates the immune system .

 

Immune system identifies these as “nonself”

B). Antibody (ies):

Binds specifically to an antigen;

 

C). Immunoglobulin: (Ig)

(Types include IgA, IgD, IgE, IgG & IgM)

 

D). Immunocompetence:

E). Immunogenenicity:

Ability to stimulate the release of specific lymphocytes and antibodies

II).  Characteristics of The Adaptive Immune Response

A). Antigen-specific:

B). It is systemic:

C). It has "memory"

III). Types of Antigens

A). Complete Antigen

These are not necessarily complete cells.

1). Immunogenenicity

2). Reactivity:

B). Hapten or Incomplete Antigen

1). reactivity but not immunogenicity.

2). It does not elicit a specific antibody.

C).  Antigenic Determinants

.

IV). Antibodies (Immunoglobulins)

Gamma globulins

A). Structure

• T or Y shaped formed by
• 4 linked polypeptide chains

• 2 heavy & 2 light chains.

•  variable region:
• constant region:

 

B). Classes

1). IgM:

2). IgG:

3). IgD:

4). IgA:

5). IgE:

C). Antibody effect

 

1).  Fixation

Binds to antigen and marks it

 

2). Inactivates by

i). Neutralization

ii). Agglutination.

iii). Precipitation

 

V). Lymphocytes:

Cells of the Adaptive Immune System

A). Characteristics

1). Self-tolerant: can identify self

2).  identify only one specific antigenic determinant

3). This ability is genetic.

 

B). Type of Cells

1). T-lymphocytes: (T-cells)

i).  Helper T-cells or CD4 cells

ii). Delayed Hypersensitivity Cells (TDH)

iii). Cytotoxic T-cells (killer T-cells) or CD8 cells

iv). Suppressor T Cells (Ts)

v).  Memory cells

2). B-lymphocytes

i), Plasma Cell:

ii). Memory cells

3). Antigen-presenting Cells (APC)

VI). Types of Adaptive Immunity

A). Antibody-Mediated Immunity or Humoral Immunity-----B Cells

 antibodies

1). bind to foreign material and cells

2). mark them for destruction by the phagocytes.

B). Cell-Mediated Immunity-----T Cells

 activated T-cells, which directly lyse:

1). infected cells

2). cancerous cells

3). cells of foreign grafts

T-cells also release chemicals that regulate the immune response.

VII). Humoral Immune Response:  B-cells

A. Primary Immune Response

Step 1). B-cell is activated

Step 2). Linked receptors are engulfed.

Step 3). Clonal selection

Step 4). Plasma cells that secrete antibodies

B. Secondary Immune Response

Step 5) Memory cells.

Step 6) Same antigen elicits clones of the ancestral cells

 

C.   Active & Passive Immunity

1). Active Immunity

i). Naturally acquired:

ii). Artificially acquired

2). Passive Immunity

i). Naturally acquired

ii). Artificially acquired:

 

VIII). Cell Mediated Immune Response (T-Cells)

T-Cells

Class I:

Class II:

 

Reaction to an Antigen presenting cell

Step 1: Antigen Binding

 

 

 

Step 2: Co-stimulation

 

 

Depending on the site that is bound the T-cell will be pushed to complete activation or to stop activation.

Without the signal the T-cell remains unresponsive.