Antigens. Antigen structure of the microorganisms. Immune

cells and their markers

Antigen Antigen may be any non-self foreign

substance to which lymphocytes respond Any antigen consists of:

1. Epitope

2. Non-specific remaining portion

Classification:

1. Complete antigens

2. Haptens (complex and simple)

Properties of the antigens

Foreignness Antigenicity Specificity High molecular weight Solubility or colloidal properties

Antigen specificity.

1. Heterogenic specificity

2. Species specificity.

3. Isospesificity.

4. Autospecificity

Antigen structure of the bacterial cell

O-Ag K-Ag H-Ag Vi-Ag

Other bacterial antigens:

Protective antigens Bacterial exotoxins and enzymes

Specificity of bacterial antigens Genus antigens Species antigens Group specific antigens. Type specific antigens.

Structure of the immune system

Lymphoid system consist of the: Lymphoid cells (T and B cells) Lymphoid organs:

1. Central (primary) organs: thymus and bone marrow2. Peripheral (secondary) lymphoid organs are:

T-cells may be subdivided into some subsets (or subpopulation) due to their functions:

1. T- helper (TH)

2. T- suppressor (TS)

3. T- regulator (TR)

4. T- cytotoxic (TC);

5. Delayed-type hypersensitivity T cells (TDTH);

B-cells Activated B-cells can differentiate into

plasma or memory cells

Cytokines1. Monokines

2. Lymphokines

3. Interleukins (IL)

Types of immune response

Cellular immune response Humoral immune response Immunological memory Immunological tolerance Hypersensitivity reactions

Immune response to an antigen may be of two broad types:

The humoral or antibody mediated immunity (AMI). It is mediated by antibodies produced by plasma cell The cellular or mediated immunity (CMI). It is mediated by sensitized T-cells

Cellular cooperation in the immune response

1. Antigen processing cells (APC) (macrophages or dendritic cells)

2. TH cell (either Th1 or Th2)

3. Either B-cell in the humoral immune response or TC (TK) cell in the cellular immune response