When you are a kid at home, you wanna be something, but you don’t know what. You are at the pro-something stage of your life. You could be a pro-science or a pro-arts.
Similarly, in the bone marrow, pro T cells know they wanna be a T cell but they don’t know which one. Pro T cells are double negative, that is, CD4 -ve and CD8 -ve.When you go to school, you wanna become everything! You wanna be a doctor and a singer and they have nothing in common. Your parents tell you that you are being immature, that you should choose one. But you dream on being both =)
Similarly, when T cells enter the thymus, they are double positive, that is, CD4 +ve and CD8 +ve. They are known as the immature T cells. The thymic cortex is where you’d find them.You go through school and college, like and dislike things and finally decide on one. That is when you become mature.
Similarly, T cells go through the thymic cortex and medulla, have their positive and negative selection, and decide whether they are CD4 +ve or CD8 +ve. At this stage, they are called mature T cells.Then you finally pursue your dream, reside in your home and be useful when needed.
Similarly, T cells live in the Periarteriolar lymphoid sheaths, and come to the rescue when they are presented with blood borne antigens via myeloid dendritic cells.
Thank you for the compliments =)
My advice to you is, if you can’t understand things, think of pizza!
Immunogenicity is the ability to induce a humoral and/or cell-mediated immune response.
If you can convince your mom to make pizza, you are immunogenic (Or pizza-genic!)
Antigenicity is the ability to combine specifically with the final products of the immune response (i.e. secreted antibodies and/or surface receptors on T-cells).
If you can eat the pizza (bind to the final product of what your mom made) you are antigenic.
Fact: Although all molecules that have the property of immunogenicity also have the property of antigenicity, the reverse is not true.
If you are making your mom make pizza, duh, you ARE gonna eat it. If you are immunogenic, you are also antigenic.
But say, your dad comes home and he sees the pizza and eats it. He didn’t induce your mom to make pizza (not immunogenic) but he ate it anyway (antigenic).
Hope it clears things up. Now I’m gonna go eat a pizza ;)
Here’s a complete guide on how to remember the HLA associations. Let’s catch em all!
Doctors (DR) will turn into MD’s someday.. The thought makes you go, “Aah”
Starting with 2 and ending with 5, your mnemonic for DR associations is "MD.. AAH!"
HLA DR2 - Multiple sclerosis
HLA DR3 - Diabetes mellitus type 1
HLA DR4 - Arthritis (Rheumatoid, also the one associated with Lyme’s disease)
HLA DR5 - Anemia (Pernicious, causing B12 deficiency)
HLA DR5 - Hashimoto’s thyroiditis
If it’s not too much, you can remember “Hey! This Doctor is going to be good MS someday” to remember Hay fever, Goodpasture’s syndrome and Multiple Sclerosis for HLA DR 2.
Hi5 is another way you can remember about Hashimoto’s relation to DR5.
HiPA5 will help you remember Pernicious Anemia with it too (If the A’s of Arthritis and Anemia confuse you!)
I use rhymes for all the other associations, make sure you sing em with a funny tone!
"Two, three S-L-EE.
Three, four, not so sour.”
HLA DR2 and HLA DR3 is associated with SLE
HLA DR3 and HLA DR4 is associated with Diabetes mellitus type 1
(not sour - sweet - sugar - diabetes lol)
You can also remember with the pokemon, "Two, three, butterfree" for the butterfly rash in SLE.. Whatever suits you.
“A three, FrEaking three.”
HLA A3 is associated with Hemochromatosis.
(fe3+ - iron - hemochromatosis)
”Be there at eight, don’t be late.”
HLA B8 is associated with Grave’s disease.
(late - dead - grave)
”Seven, heavenly pee.”
HLA DR7 is associated with steroid-responsive nephrotic syndrome.
(pee - kidney - nephrotic syndrome)
Seven rhymes with heaven, lee rhymes with pee, I don’t know what I was even thinking when I made this!
For HLA B27, the PAIR mnemonic is famous.
Psoriasis, Ankylosing spondylitis, Inflammatory bowel disease, Reiter’s syndrome.
The above mnemonics will suffice for the exam.
The below facts are not very high yield, but for the sake of completion here you go -
SCAM 3 - Sjogrens syndrome, Chronic active hepatitis, diabetes mellitus type 1 for HLA DR3.
If you extend the line in 4, it looks like an A.
A for Arthritis. Flip the A and it looks like V.
V for vulgaris, pemphigus vulgaris.
So HLA DR 4 is associated with Arthritis as well as Pemphigus vulgaris,
Hope it helps you all < 3