# data[].attributes.body
- Classes of antibodies are IgG, IgA, IgM, IgE, IgD, produced by plasma cells
- antibodies clear extracellular pathogens
- Memory B cells are in the circulatory system after an infection
- Main functions of B cells are producing antibodies, acting as antigen-presenting-cells (APC) and producing memory B cells (to recognize same antigen upon next infection)
- Function of antibodies include neutralization, complement activation, opsonization

# data[].attributes.body
- T cells are produced in the immune system only after an infection
- T cells consist of cd4 and cd8
- CD4 --> proliferate and differentiate into T helper cell (Th1 & Th2)
- CD8 --> proliferate and differentiate into cytotoxic T cell (Tc)

# data[].attributes.body
1) Why are there so many types of T-cells and do they have the same function?

2) Why does T-cells fall under acquired immunity?

# data[].attributes.body
1) All T cells have their own function

2) 3 signals to activate T cells are antigen recognition, co simulator and cytokines (IL-2). Antigen recognition is where the pathogen that enter the body will be engulfed by macrophage into antigen fragment. This will be expressed on surface of macrophage as MHC Class II which will be recognized by T cell later. Secondly, the co-simulators is where CD28 will bind to B7 which will activate T cell. Lastly, cytokines which is IL2 will bind to IL2 receptor which cause the T cell to proliferate into other type of T cell

# data[].attributes.body
1.What does this generally do to the immune system?

2.How does the antibody-antigen complex works?

3.How do antibodies differentiate or switch to other types of immunoglobulin?

4. What are the functions of each antibodies produced?

5.What is somatic hypermutation and isotype switching ?

# data[].attributes.body
1. B cells are involved in the adaptive immunity, mainly in the production of antibodies. When B cells are stimulated by antigen, they proliferate and differentiate into plasma cells, to produce antibodies specific to the presented antigen. Antibodies are involved in neutralization, complement activation and also opsonization in order to remove pathogens.

2. Specific antibodies will bind to target cells with the specific antigen. In one mechanism, the antibody-coated pathogen then binds to Fc receptors on macrophages, leading to the pathogen's phagocytosis. NK cells can also recognize the antibodies bounded to the target cell, and lead to their apoptosis.

3. 3 factors account for antibody diversity, which are genetic diversity, combinatorial diversity and junctional diversity. Genetic diversity refers to the arrangement of heavy and light chain loci, whereas the combinatorial diversity refers to the random selection of one gene segment of each V, J and D type. Junctional diversity refers to the random addition of nucleotides during joining.

4. IgM are the first antibodies produced after infection, binds to complements. IgG are dominant after acute infection, neutralize toxins. IgA protects mucosal surface. IgE are involved in mast cell and eosinophil degranulation. IgD are usually co-expressed with IgM but have unknown function.

5. Somatic hypermutation is a process where there is introduction of nucleotide substitutions throughout the variable regions of the rearranged Ig heavy and light chain genes. Isotype switching is the genetic rearrangement of gene segment encoding the constant region, where antibodies of the same antigen specificity but different effector functions are produced.

# data[].attributes.body
- Three activation pathways which are alternative, classical, and lectin pathways
- All pathways are triggered by different factors and involve many different proteins
- Classical pathway is antibody-dependent while alternative and lectin pathways are antibody-independent.
- Formation of membrane attack complex as the main action to remove pathogens

# data[].attributes.body
1. What are the other functions of complement besides getting rid of pathogens via MAC?

2. How is complement system related to macrophages?

3. How does complement system helps in activating the other immunity and what are the necessary molecules needed?

4. How does the complement pathway cause inflammation?

# data[].attributes.body
1. There are more pathways that will stimulate the immune response besides the formation on MAC include phagocytosis, inflammation, immune clearance, chemotaxis , neutralizing viral infectivity and inducing adaptive immunity.

2. Macrophages play a role in the complement pathway where they phagocitize pathogens. For example, when C3b is bounded to pathogen, they act as effective opsonin and lead to the phagocytosis of the pathogen.

3. Lectin pathway binds to carbohydrates on pathogen surface, alternative pathway binds to microbial cell wall (glycoprotein) and classical pathway binds to antigen-antibody complex.

4. Complement activation plays a big role in inducing inflammation. After activation which leads to an enzyme cascade, C3 convertase cleaves C3 into C3a and C3b. C3a mainly acts as anaphylatoxins. C3a will induce degranulation of mast cells to release histamines. It will also lead to smooth muscle contraction and increase vascular permeability of cells, thus attracting phagocytes to the site of antigen entry. This action will further induce inflammation.

# data[].attributes.body
- activated by PRRs found on macrophages membrane (PAMPs can recognize)
- derived from monocytes
- main functions are phagocytosis, produce pro-inflammatory cytokines and act as antigen-presenting-cells (APC)
- MHC plays an important role in their mechanism
- Macrophages also play a role against virus infected cells

# data[].attributes.body
1. How does the inflammatory cytokines cause fever?

2. What are the important PRRs found on macrophages?

3. How does macrophage act as APC?

4.What cells and cytokines are involved in the mechanism?

5. Does macrophage involve in removing pathogens only?

# data[].attributes.body
1. Interleukin-6 which is released by macrophages is an endogenous pyrogen that induces fever.

2. PRRs found on macrophages are TL receptors

3. Macrophages have MHC class I and class II that will bind to antigens. After binding, antigen-MHC complex will further bind to respective Tcells. (CD4 Tcell and CD8 Tcell)

4. Important cytokines released by macrophages can be classified into pro-inflammatory (TNF-a, IL-6, IL-12) and anti-inflammatory cytokines (TGF-B, IL-4).

5.Macrophages not only removes/engulf pathogens, but they also remove dead cells