DICTIONARY

T-Cell Development

Positive selection: Is the selection of cells whose T-cell receptors respond to self-MHC. 

Negative selection: Is the selection against cells whose TCR react strongly to self-MHC combinations. 

Double Negative: This is when the fetal development of T-cell is TCR-independent and lacks the CD4+ and CD8+. So, the DN are CD4- & CD8-.  

Affinity Hypothesis: advanced model that is used to explain the paradox of MHC-dependent positive and negative selection. It asserts the differences in the strength of TC-mediated signals received by thymocytes undergoing the positive and negative selection indicating the result of the interaction. 

Intraepithelial lymphocytes: are mostly CD8+ cells that contain the features of the innate immune cells and patrol the mucosal surfaces. 

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DICTIONARY

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1. Endogenous (cytosolic) pathway:  the pathway involved in waste products from self-cells and Ag-recognition on the MHC Class I. Peptides that are broken down by proteolysis, and are transported from the cytosol to the rough ER (where catabolized peptides go to, to meet up with MHC I & TAP is), to the Golgi (where proteins are modified), and then the vesicles (where proteins are kept). When proteosome cuts off the protein, it diffuses into the cells by tapasin. Now, proteins arrive on MHC class I molecules.

2. ITAM: Immunoreceptor tyrosine-based activator motif sequences amino acid in the cytoplasmic tail (that contains serine) and repeats itself more than once. 

3. Invariant chain: non-MHC encoded protein interacts with the class II peptide-binding groove preventing any endogenously derived peptides from binding while the class II molecule is withing the RER. 

4. Double-negative (DN) cells: these are fetal T cells that lack both CD4 & CD8 cells. 

Reference

For more cartoons, visit: 

http://immense-immunology-insight.tumblr.com/page/6

INVESTIGATION

Transporter associated with antigen processing (TAP)

TAP is a membrane-spanning heterodimer that consists of two proteins, which are TAP1 and TAP2. The TAP1 & TAP2 each have their domains that appear in the rough endoplasmic reticulum and an ATP-binding domain appearing in the cytosol. TAP is found in the cell membranes of bacteria. They mediate ATP-dependent transport of sugars, amino acids, and peptides. These protein transport peptides that interact with MHC class I. However, there is a thing as TAP deficiency, and this is when there's a downregulation of peptide uptake and no new MHC class I molecules are produced. An example of this condition is the bare lymphocyte syndrome (BLS)--a defect in TAP1 and TAP2 gene. The lymphocytes in patients suffering from this disorder refuse to express MHC molecules, and if they do, it is below average levels. There are type1 BLS & type2 BLS. In type 1, MHC class I molecules are not being expressed while in type 2, expression of MHC class II is not being expressed. Besides peptides unable to bind to class I molecules, other abnormalities are increased NK cells and decreased levels of CD8 T-cells. I believe the reduced levels of CD8 is due to the lack of CD4 cells since they activate both B cells and cytotoxic CD8 cells. And because of this, their ability to fight off infections is significantly affected, individuals tend to get viral and bacterial infections often. Although, I think the NK cells are elevated because it just makes sense. If your other cells needed to fight off infections aren't working, the cells you have that works would be twice as active. So, If your CD4 cells required to destroy a pathogen is absent, then the ones you do have would have to work twice as much; and maybe that might fight off some viral infections if possible.
Other [visible] symptoms include chronic skin lesion, sinusitis, possibly constipation, and anemia.
Treatments: bone marrow transplant, and possibly gene therapy.

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References

•  Gadola, S. D., H. T. Moins-Teisserenc, J. Trowsdale, W. L. Gross, and V. Cerundolo. "TAP Deficiency Syndrome." Clinical and Experimental Immunology. Blackwell Science Inc, n.d. Web. 10 Nov. 2016. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1905688/>.
• https://rarediseases.info.nih.gov/diseases/8427/bare-lymphocyte-syndrome

#happybloggin' :)

Biochemistry vs. Immunology

ENCOUNTER

In Biochemistry: We are currently discussing carbohydrates and their functions in an organism. 

• Oligosaccharides are carbohydrates molecules composed of little monosaccharides unit. 
• Polysaccharides are multiple molecules of sugars. 
• Glycosphingolipid: lipids that come from ceramides that contain sugars/glucose. 

Polysaccharides contribute to the blood types, which are A, B, AB, & O. There are different kinds of polysaccharides (sugars), and the combination of these sugars determine the blood type of an individual. Human blood groups depend on the enzyme that catalyzes formation of the glycosidic bond. The O antigen contains (Lipids- Glucose-Galactose-N-acetylglucosamine-Galactose-Fucose)

Blood type A is composed of the same sugars above but rather N-acetylgalactosamine. The genes in a person's DNA encodes for a specific transferase enzyme for the addition of the blood type an individual is bound to have. So in plain terms, if a person's gene code for type A or type B transferase, the person would have blood type O. 

In immunology, blood type O has no antigens on the erythrocytes, blood type A has B-antigen, blood type B has A-antigen, and blood type AB has both antigens. This is why an individual gets a blood transfusion from another person with a similar blood type. Antibodies circulating the person's blood will attack RBCs that are a mismatched of theirs. 

Conclusion, In Immunology, it's about the antigens and biochemistry is how you get the antigens. Biochem discusses the structure and immunology talks about the effects of it; it elaborates more on what the antigen does. Biochemistry is about the structure of the proteins while Immunology is the function of the proteins. 

There are a lot of ways to relate biochemistry and immunology, but this is just a brief summary. To learn more about this topic,  here are websites: 

• http://biology.stackexchange.com/questions/26374/why-can-blood-group-o-be-given-to-all-blood-groups
• https://en.wikibooks.org/wiki/Structural_Biochemistry/Carbohydrates/Blood_Type
• https://www.quora.com/How-are-polysaccharides-helpful-in-determining-the-blood-group

#happybloggin' :)