Precipitation vs. Agglutination

[MudPhud20XX]

So Kaplan immuno explains these two terms as below:
1. Precipitation: soluble proteins become insoluble
2. Agglutination: particles settle out of suspension

Honestly, I feel like they are still very similar.

So the precipitation of the Ag-Ab complex is used let's say for hepatitis when you know that HBsAg is gone and you know that's during the equivalence zone (window period).

When you do Direct or indirect Coomb's test, don't you also get to see the precipitation in the test tubes due to the fact that antibodies binding to antigens?

I feel like they are playing with words. Can anyone please help me out?

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[Transposony]

Precipitation reactions differ from agglutination reactions in the size and solubility of the antigen and sensitivity. Antigens are soluble molecules and larger in size in precipitation reactions.

Agglutination reaction vs Precipitation reaction
• Major difference between precipitation and agglutination is the size of antigens involved.
• Antigens are soluble in case of precipitation while they are insoluble in agglutination
• Agglutination is more sensitive than precipitation.

Agglutination reaction

Precipitation reaction

 

[Dr Ren]

Transposony,
Do you know in what way agglutination is more sensitive than percipitation?
I've been looking to see where you got that idea from and I didn't see that idea in the links you provided... nor do have I seen it in the textbooks I've been using. Thanks.

 

[Transposony]

Transposony,
Do you know in what way agglutination is more sensitive than percipitation?
I've been looking to see where you got that idea from and I didn't see that idea in the links you provided... nor do have I seen it in the textbooks I've been using. Thanks.

Agglutination is more sensitive than precipitation reaction because it takes a lot of more soluble antigens and antibody molecules to form a visible precipitation.
In other words, it can't visibly detect small amount of antigen. So it's specific (antigens/antibody reaction) but not as sensitive as agglutination.
You can, however, convert a precipitation into agglutination reaction by attaching soluble antigens to large inert carriers such as erythrocytes or latex beads.

 

[Phloston]

So Kaplan immuno explains these two terms as below:
1. Precipitation: soluble proteins become insoluble
2. Agglutination: particles settle out of suspension

Honestly, I feel like they are still very similar.

So the precipitation of the Ag-Ab complex is used let's say for hepatitis when you know that HBsAg is gone and you know that's during the equivalence zone (window period).

When you do Direct or indirect Coomb's test, don't you also get to see the precipitation in the test tubes due to the fact that antibodies binding to antigens?

I feel like they are playing with words. Can anyone please help me out?

I would think precipitation just means coming out of solution as an umbrella term (i.e., non-specific). But agglutination means coming out of solution because of a chain reaction binding process that causes insolubility (i.e., change in size/charge of particles); so agglutination is a type of precipitation (more specific).

You could think Ca3(PO4)2 could precipitate out of solution as individual molecules, but RBCs agglutinate out with IgG (eg warm AIHA) or IgM (eg cold AIHA) as agglomerations.

 

[Phloston]

Btw I just noticed the roots are the same for agglutinate and agglomerate. Yeah, so I'm sticking to my guns here!

 

[Dr Ren]

Agglutination is more sensitive than precipitation reaction because it takes a lot of more soluble antigens and antibody molecules to form a visible precipitation.
In other words, it can't visibly detect small amount of antigen. So it's specific (antigens/antibody reaction) but not as sensitive as agglutination.
You can, however, convert a precipitation into agglutination reaction by attaching soluble antigens to large inert carriers such as erythrocytes or latex beads.

That makes sense. I was thinking of the two in terms of the reactions that might happen during an immune response... along the lines of which antibodies would be more sensitive/effective. Now it makes perfect sense. If we are talking about lab tests the clumping of cells would certainly be more visible at lower concentrations than smaller particles like molecules or even viruses. Thanks for clearing that up!