Monday, February 16, 2015

Study group discussion: Types of hypersensitivity reactions

*We were discussing lepra reactions when we diverted to hypersensitivity reactions the other day*

I can't remember the types.

Here's a life saver for your soul -  http://medicowesome.blogspot.ae/2012/03/hypersensitivity-types-mnemonic.html

Apparently there is type 5 and type 6 hypersensitivity reactions too.

5? What's type 6? Oh my god.

I had received a long fan mail on it a few days back:
We had a test about 4 days ago on hypersensitivity reaction type 5 and a lot of people left it blank because they thought it was a typo. Well, I later found out that it is the same as type 2 non cytotoxic (In fact, there is a type 6. Can you believe it? ). In situations like this, I always imagine there is a bored researcher sitting in a corner of his office, maybe eating a donut and taking a sip of milk from a beaker or conical flask, who thinks the best pass time activity is to screw around with the heads of medical students. So he gets his iPad, types a whole new ( and sometimes unnecessary) classification, sends it to a journal thus forcing medical students to add one more thing to that cramped up space called the head.

Hahahahha. The fanmail is hilarious. Made my day! :D

Myasthenia gravis? Which type of hypersensitivity reaction?

Myasthenia is type 2. So is Grave's.

Nope. It's Type 5.

Why?

Type 5 is an extension of 2.

It is because of it's blocking antibody, right? Or because it doesn't incite any inflammation?
In that case what would Graves be that antibody is stimulating?

Graves and gravis are caused due to effect of cellular functions. Graves - Increase in cellular functions. Gravis decrease in cellular functions.

"Instead of binding to cell surface components, the antibodies recognise and bind to the cell surface receptors, which either prevents the intended ligand binding with the receptor or mimics the effects of the ligand, thus impairing cell signaling.

Some clinical examples:

Graves' disease
Myasthenia gravis

The use of Type 5 is rare. These conditions are more frequently classified as Type 2, though sometimes they are specifically segregated into their own subcategory of Type 2."
- Source: Wikipedia

So type 5 includes autoimmunity, right?

Yes.

I didn't know they had classified it under autoimmunity now. Got it!

Type 6 is Antibody Dependent Cell Mediated Cytotoxicity.. The NK cell stuff.

They kill viruses laden cells and tumors.

Basically, any antibody that causes a effect besides inflammation due to binding to cell receptors is type 5.

Immunology comics on ADCC :D http://immense-immunology-insight.blogspot.ae/2013/10/functions-of-antibodies-simplified.html

Okay, review questions!
Name type of hypersensitivity!

Poison ivy reaction after 48 hours in a camping trip.

Type 4.

Correct!

A person who was given horse serum for something.

Type 3. Type 1 if he presents early!

Good job!

Person underwent a screening test for tuberculosis.
Type 4.

Excellent!

Person develops hemolysis after receiving penicillin.

Type 2.

Oh kid gets a bee sting.

Type 1.

Person with leprosy develops new lesions after starting drug therapy.

Type 3.

Awesome!

Hypersensitivity pneumonitis?

It is both type 3 as well as type 4.

1 comment:

  1. Ikan! I was searching something like this on hypersensitivity. 😀

    ReplyDelete

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