IgM is made first but the IgG is what gives lasting immunity. This happens when the antigen in the vaccine is a protein, like diphtheria toxin, and you get a thymus dependent response. CD4+ T cells stimulate B cell class switching to IgG.
This is opposed to a capsular polysaccharide antigen like the pneumococcal polysaccharide vaccine that is thymus independent. The B cells can't undergo class switching because the antigen isn't a protein so only IgM is produced and the immunity is short lived.
STAGES of B CELL DEVELOPMENT goes like this!
You got three stages!!! On the boards, they’ll describe it and you have to pick which stage!!! In the pre-B cell all you see is Mu change. Mu as in IgM within the cytoplasm! IN THE PRE-B cell ALL you see is MU CHANGE in the cytoplasm!!!
In the IMMATURE B CELL, you See some of that IgM on the SURFACE, which tells you that the first antibody secreted by every BCELL is IgM. That means when a a baby is born….which Ab is he going to secrete first?? ANS: IgM!!!
Does everybody (now) realize that why an ELIZA test that tests for IgG is WORTHLESS in a ababy! Just so you don’t just memorize that!!! The baby doesn’t even make IgG when he is born, so why even do an ELIZA TEST that checks for IgG!!
Oh...when it is a MATURE B cell, IgM and IgD is on the surface...think MD
THE PRIMARY RESPONSE?? THAT MEANS THE FIRST TIME THAT YOU COME INTO CONTACT WITH AN ANTIGEN!!! The first antibody is gonna be which one?? ANS: IgM!!!
So tell me, if IgM doesn’t show up in 3 days, who the heck is protecting me for three days???? This is in anybody..just know and tell me who protects me for 3 days if IgM doesn’t show up until DAY 3. ANS: the neutrophils!
Who protects me in the first three days…its gotta name: it’s the NEUTROPHILS!!
(REMEMBR) that it (the neuts) show up at 24 hrs and peak at day 3!!!
