Bloque 1: Introduction

Question 1

Cellular components of the innate response

Answer 1

Phagocytic cells:

• Monocytes
• Macrophages
• Neutrophils

Mediator cells:

• Mast cells
• Basophils
• Eosinophils

Cytotoxic cells:
- Natural killer cells

Question 2

Humoral components of the innate response

Answer 2

Complement
Cytokines
Other proteins: RCP, MBL…

Question 3

Properties of the innate response

Answer 3

Not specific
Limited
No memory

Question 4

Properties of the adaptive response

Answer 4

Specific
Memory
Education (self and non-self differentiation)
Large repertoire (10^11 different receptors)
Homeostatic

Question 5

Humoral and cellular response

Answer 5

Humoral response is characterised by being performed by different molecules such as antibodies or complement proteins. Humoral response is mediated by antibodies, which are secreted by B-cells. Antibodies can recognise microbes and they are the principal defense mechanism against microbes outside the cell and their toxins. Humoral response is usually related to extracellular pathogens.

Cellular response is mediated by T-cells. T-lymphocytes are used in the response to viral infections, as they’re able to recognise cells which have been infected by a virus and destroy them.

Question 6

Lymphoid cells

Answer 6

T cells are the cells whose receptors are used to recognise antigens. According to their cluster of differentiation, they can be divided into several subpopulations of cells among which we can find CD4 cells and CD8 cells. These lymphoid cells mature in the thymus.

B lymphocytes are cells that produce antibodies. Their maturation process takes place in the marrow bone and they are 5-10% of lymphocytes in blood.

Null cells are those cells with cytotoxic activity. These cells can be divided into natural killer cells, granular lymphocytes and NK1-T cells (which are further divided into T cells and NK-like cells)

Question 7

Myeloid cells

Answer 7

Mononuclear cells:

• Monocytes: Induce tissue inflammation
• Macrophages: Induce tissue inflammation, present antigens to T cells and have phagocytic activity

Granulocytes:

• Neutrophils: Most abundant. Bacterial infection
• Eosinophils: Parasitic infections, cancer and allergic reactions
• Basophils: Allergic reactions

Mast cells: Parasites and allergic reactions

Dendritic cells: APC

Question 8

Primary lymphoid organs

Answer 8

Thymus: T-lymphocyte maturation and education

Spleen: Blood filtration and phagocytosis of damaged and aged erythrocytes. Proliferation of B and T lymphocytes and production of antibodies by plasma cells.

Lymph nodes

Bone marrow: B-lymphocyte maturation

Question 9

Secondary lymphoid organs

Answer 9

Lymph nodes: Collects lymph

Mucosa-Associated Lymphoid Tissue (MALT): Solitary lymphatic nodes present mainly in the GI tract, but also in the respiratory and urinary tracts. They act as a first line of defense

Tonsils: Lymphatic follicles with germinal centre

Question 10

Definition of antigen, immunogens, epitope, antigen determinant, hapten and paratope

Answer 10

Antigen: Any substance that binds specifically to TCR or antibodies

Immunogen: Type of antigen that produces an adaptive immune response

Epitope: Part of the antigen recognised and bound to the antibody or TCR/MHC complex

Antigen determinant: Epitope

Hapten: Low molecular weight molecule that can be made immunogenic by the conjugation to a suitable carrier

Paratope: Region in the variable domain of the antibody or T-cell that interacts with the antigen

Question 11

Difference between antigenicity and immunogenicity

Answer 11

Antigenicity of proteins is a CHEMICAL property describing the interaction between epitopes and paratopes in terms of chemical and structural complementarity.

On the other hand, immunogenicity is the ability of a protein to give rise to an immune response in a competent, vertebrate host. It is a BIOLOGICAL property existing only in the biological context of the immune system.