General Immunology

Question 1

Why are monocytes and mast cell not considered granulocytes even though they develop form the myelocytes progenitor cells (cell that make all granulocytes)

Answer 1

Mast cells do have granules in them but they stay in tissues only while other cells are travelling in blood
monocytes are travelling in blood when comes to the tissue they become macrophages

Macrophages are the main antigen presenting cells.

Question 2

Explain Immune system.

Answer 2

Inate and acquires
innate is quick response and first line of defence including cells such as granulocytes, macrophages, complementary protiens and inflammatory mediators

acquired is delayed response and second line of defence including B cells

the connecting link between these two are the T cells.

Once t cells are activated with the APC’s they can either become t killer and kill cells or t helpers which activate b cells

Question 3

What is the role of dendritic cells? (Myeloid lineage)

Answer 3

Dendritic cells are a type of antigen-presenting cell (APC) that form an important role in the adaptive immune system. The main function of dendritic cells is to present antigens to the t cells and the cells are therefore sometimes referred to as “professional” APCs.

Question 4

What are the roles of Natural killer cells? (From lymphoid lineage)

Answer 4

Natural killer cells (also known as NK cells, K cells, and killer cells) are a type of lymphocyte (a white blood cell) and a component of innate immune system. NK cells play a major role in the host-rejection of both tumours and virally infected cells.

Question 5

How the Lymphoid precursor cells (t cell precursors ar attracted to the thymus?

Answer 5

Thymus releases chemicals such as Thymosin,thymotaxin, thymoppoetin and thymic factors to attract them.

Question 6

What are the functions of the chemicals (Thymosin,thymotaxin, thymoppoetin and thymic factors) once the premature cells ebters the thymus

Answer 6

The pre mature cel is receptor less
these chemicals activates the gene RAG1 and RAG2
inside the pre mature thymus cell
these genes when activated leads to the formation of TCR on the surface of the cell
This TCR can be specific for any antigen.

Question 7

What are CD4 and CD8? (Co receptors0

recognition of the MHC molecules is mediated by co receptors

(RECOGNITION and ADHESION molecules)

Answer 7

These are clusters of diffrentiation

The cluster of differentiation (CD) designation refers to proteins found on the surface of cells.

. Each unique surface molecule is assigned a different number, which allows cell phenotypes to be identified. Surface expression of a particular CD molecule is useful for the characterization of cell phenotypes

basically these are unique protien molecule on the surface of cells
each cell have different diffrentiation protien with different assignes number

these protiens help in cell identification

CD 4 attracts MHC class 2 molecules (present on b cell , dendritic cells and APC)

CD 8 attract MHC class 1 (nucleated cell) (CD8 brings the T cells to MHC class 2 of other cell containing weird protiens (mostly from cancer cells)

Question 8

how can B cell be activated ?

Answer 8

Either antigen comes and binf to the membrane Antibodies on the B cells
or
by t helper stimulation (see the notes)

Question 9

Explain the structure of the MHC class 1 molecule (on the nucleated cell)

Answer 9

45kDA
3 domains
each domain 90 amino acids
inserted into cell membrane through a transmembrane domain of 25 amino acid
cytoplasmic tail 30 hydrophilic amino acid