Polysaccharide vaccines & thymus-independent antigens

[Ven0m]

Polysaccharide vaccines (consisting of only polysaccharide, no protein) generate only IgM because they're thymus-independent antigens.
So does this mean they do not generate memory (unless conjugated with a protein, allowing them to cause T-cell dependent activation of B-cells)?

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[Rahas]

Yes, this is why their immunity doesn't last as long as those of T dependent antigens.

 

[Ven0m]

Yes, this is why their immunity doesn't last as long as those of T dependent antigens.

So after IgM is all gone, there will be no immunity? Half life of IgM is pretty short.

 

[FindersFee5]

So after IgM is all gone, there will be no immunity? Half life of IgM is pretty short.

I could be wrong on this, but it's not just the IgM response - it's the B cells producing IgM that have been activated by the vaccine. These end up living longer (I think in the range of 5-10 years?). If they get triggered again they can produce a quick and strong IgM response.

 

[Ven0m]

I could be wrong on this, but it's not just the IgM response - it's the B cells producing IgM that have been activated by the vaccine. These end up living longer (I think in the range of 5-10 years?). If they get triggered again they can produce a quick and strong IgM response.

Are those memory B-cells? Because from what I've read, B-cell memory is only generated if they were activated by T-helper cells (also required for formation of germinal centers, class switching, and affinity maturation). Are the B-cells you're referring to a different type of memory?

 

[FindersFee5]

Are those memory B-cells? Because from what I've read, B-cell memory is only generated if they were activated by T-helper cells (also required for formation of germinal centers, class switching, and affinity maturation). Are the B-cells you're referring to a different type of memory?

No, they're not memory b cells, they're just mature B cells, but they still live for 5-10 years. Memory b cells are with you for the rest of your life I think.

 

[Ven0m]

No, they're not memory b cells, they're just mature B cells, but they still live for 5-10 years. Memory b cells are with you for the rest of your life I think.

Ohh thanks man!

 

[navigator]

I could be wrong on this, but it's not just the IgM response - it's the B cells producing IgM that have been activated by the vaccine. These end up living longer (I think in the range of 5-10 years?). If they get triggered again they can produce a quick and strong IgM response.

The IgM-producing plasma cells most likely return to the bone marrow where there's a favorable environment for them to live longer than they would in the bloodstream. (This is also why plasma cells return to the bone marrow after the whole B cell activation process - they last longer there than anywhere else, although it's still not as long as memory B cells.)

 

[Ven0m]

The IgM-producing plasma cells most likely return to the bone marrow where there's a favorable environment for them to live longer than they would in the bloodstream. (This is also why plasma cells return to the bone marrow after the whole B cell activation process - they last longer there than anywhere else, although it's still not as long as memory B cells.)

What I read in "How the Immune System Works" by Sompayrac is that activation of naive B cells in a primary immune response produces three kinds of B cells:
1. Short-lived plasma cells: migrate to the bone marrow/spleen, produce huge quantities of Abs specific for the attacker, but only live for a few days
2. Long-lived plasma cells (memory B cells): migrate to the bone marrow to produce more modest quantities of Abs; responsible for the Abs produced that provide life-long immunity
3. Central memory B cells (memory B cells): reside in secondary lymphoid organs, function not as Ab producers but as memory "stem cells" to replenish the pool of themselves + long-lived plasma cells that have died from old age, plus can differentiate into short-lived plasma cells in response to a subsequent attack

So I'm confused about where the plasma cells you guys are talking about fit into this picture, it seems you guys learned memory in more detail