Immunology questions

Hi Folks! I'm a newbie in this forum, I hope not to violate any rule with this post, in the case I apologize in advance

I've got a list of doubts about Immuno exam, I am a Med student

1. what is the role of lectins and agglutinines in innate immunity?

2. entrance of immature T in thymus happens via blood?

3. once T mature in the thymus, thymus then athrophyzes. Where does maturation for the next T happen? I haven't got this clear... is it like for the oocytes? they just mature all once and that's it?

4. innate immunity: what are preformed effectors? [Janeway] are they AMP?

5. CD40:CD40L is it a stimulating interaction from T towards APC? has it other functions?

6. Can DC be found in blood?

7. Th acivate B. OK. Do B in turn activate/stimulate T? as "late" APC?

8. only IgM and IgG activate complement? what about IgA and IgE?

9. how many MHC2 on a DC?

10. definition of antagonist of a cytokine

11. pH of phagosome = ? I read that pH [i.e. neutrophils] goes above 8, activating AMP, then gets back to 7, then below 7 because of acid hydrolases...

thanks from heart to everyone will explain me some of the above doubts!