Arthus reaction

[Convalaria]

Hey everyone

I got a question about soldier that comes for examination and vaccination prior to leaving for a duty. He was given immunization shot (some protein) that caused swelling and inflammation within 24 hours at the site of injection, and it is known as Arthus reaction - III type with immune complexes, which proved that his body has 'seen' this protein before.

Now here's my question:
Then what type of reaction most likely has developed after the first time exposure to this antigen? IV?

Thanks!

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[Phloston]

Now here's my question:
Then what type of reaction most likely has developed after the first time exposure to this antigen? IV?

A type-IV hypersensitivity reaction requires previous exposure to the antigen in order to induce an immune response, just as a type-III does. In other words, if you're exposed to poison ivy and develop a rash, it means you had encountered it before without a reaction and then became sensitized. This first-time exposure is just an APC-CD4+ interaction, leading to the production of CD4+ cells that, in the future, can recognize the antigen again. The initial interaction is not called a hypersensitivity reaction; only the re-exposure is.

(Btw, I've encountered the poison ivy example, with re-exposure being necessary to induce the first hypersensitivity response, in both USMLE Rx and FA Q&A)

The Arthus reaction (type-III) is similar in that it requires previous antigen exposure, but instead of being elicited by pre-sensitized CD4+ cells, IgG antibody that had been produced by plasma cells, subsequent to the initial antigen exposure, causes the reaction.

I would even go so far to say that the antigen need not be the original antigen as long as there is a degree of molecular mimicry (i.e. epitope similarity).

 

[Phloston]

By the way, immuno is one of my weaker subjects, so if someone could add to / correct / elaborate on anything I've said in the above post, that would be great.

 

[mdeast]

A type-IV hypersensitivity reaction requires previous exposure to the antigen in order to induce an immune response, just as a type-III does. In other words, if you're exposed to poison ivy and develop a rash, it means you had encountered it before without a reaction and then became sensitized. This first-time exposure is just an APC-CD4+ interaction, leading to the production of CD4+ cells that, in the future, can recognize the antigen again. The initial interaction is not called a hypersensitivity reaction; only the re-exposure is.

(Btw, I've encountered the poison ivy example, with re-exposure being necessary to induce the first hypersensitivity response, in both USMLE Rx and FA Q&A)

The Arthus reaction (type-III) is similar in that it requires previous antigen exposure, but instead of being elicited by pre-sensitized CD4+ cells, IgG antibody that had been produced by plasma cells, subsequent to the initial antigen exposure, cause the reaction.

I would even go so far to say that the antigen need not be the original antigen as long as there is a degree of molecular mimicry (i.e. epitope similarity).

Interesting. Never thought about in this detail.

Overall, you should just remember that

(1) TB-PPD reaction= Type IV hypersensitivity
(2) Tetanus/Vaccine/Arthrus reaction= Type III hypersensitivity

And you're golden. Arthrus reaction is essentially a highly localized, faster version of serum sickness.

 

[Convalaria]

thanks!

I got lost when I saw question with intradermal injection of Candida extraction to check T-cell immunity. I remembered this Arthus reaction question and also I remembered another PPD question and got a little confused with these 3 things 🙂

Also besides mechanism of reactions it is useful to remember time frames as well:
type III - with 24 hours (Arthus reaction) versus
type IV - 24-72 hour (PPD, Candida test)

So let's say..reactions to vaccination:

if it's antiviral live attenuated vaccines - stimulation of both cellular and humoral immunity - then IV type?

if it's antiviral killed vaccines - only humoral immunity, type III?

And what's about antibacterial lived attenuated and killed vaccines? also IV and III respectively?

Once again, thank you!

 

[mdeast]

thanks!

I got lost when I saw question with intradermal injection of Candida extraction to check T-cell immunity. I remembered this Arthus reaction question and also I remembered another PPD question and got a little confused with these 3 things 🙂

Also besides mechanism of reactions it is useful to remember time frames as well:
type III - with 24 hours (Arthus reaction) versus
type IV - 24-72 hour (PPD, Candida test)

So let's say..reactions to vaccination:

if it's antiviral live attenuated vaccines - stimulation of both cellular and humoral immunity - then IV type?

if it's antiviral killed vaccines - only humoral immunity, type III?

And what's about antibacterial lived attenuated and killed vaccines? also IV and III respectively?

Once again, thank you!

If you're receiving a vaccine you shouldn't have already been exposed to the antigen so you won't have preformed T-cells mounted against that antigen. So while with live attenuated vaccines you'll get a T cell response, it won't be a Type IV hypersensitivity reaction. Also, it should be much slower than 48-72 hours.

Also, remember that in trying to compare PPD's and vaccine injections....they're fundamentally very different (i.e. one is usually intramuscular injection of a vaccine vs. placement of a PPD in a pocket in the skin).

 

[Morsetlis]

First exposure will produce a weak (or no) immune response.

 

[IDoIt4Love]

Haha, I know just the question you're talking about! I missed it too! But after reading the explanation to the problem and revisiting the explanation of it in FA, the FA explanation made so much more sense!

Arthus can happen when you already have some antibodies to the antigen delivered by the injection b/c your body has already seen it before. Your antibodies form complexes with the intradermally-injected antigens, causing an inflammatory response (type III). However, I don't know that you can really assume what kind of reaction he had the first time his body saw this antigen, unless you knew what his symptoms were and their time frame.

This can also happen to people who have received multiple pre-formed antibodies (passive immunity) to a toxin in the past. Snake venom is a good example of something we would give pre-formed antibodies for...once bitten, we can't wait for the body to mount its own response! With each subsequent injection of preformed antibodies, complexes between the antibody and antigen may accumulate, especially in smaller blood vessels, causing a type III reaction.

 

[Convalaria]

Haha, I know just the question you're talking about! I missed it too! But after reading the explanation to the problem and revisiting the explanation of it in FA, the FA explanation made so much more sense!

Arthus can happen when you already have some antibodies to the antigen delivered by the injection b/c your body has already seen it before. Your antibodies form complexes with the intradermally-injected antigens, causing an inflammatory response (type III). However, I don't know that you can really assume what kind of reaction he had the first time his body saw this antigen, unless you knew what his symptoms were and their time frame.

This can also happen to people who have received multiple pre-formed antibodies (passive immunity) to a toxin in the past. Snake venom is a good example of something we would give pre-formed antibodies for...once bitten, we can't wait for the body to mount its own response! With each subsequent injection of preformed antibodies, complexes between the antibody and antigen may accumulate, especially in smaller blood vessels, causing a type III reaction.

I remember that question about a man who has several snake bites in the past that were treated with antivenom. And in a week from the last case he developed serum sickness if I don't take make mistake 🙂

Thank you all, I think I got it 🙂