Here is why Lois Lerner hasn't received immunity for her testimony...

Lois Lerner hasn't taken the steps necessary to secure immunity. If Lerner really wanted immunity, she would give Issa a proffer. This is a letter that let's Issa know what he will get in return for granting immunity. If Lerner has nothing interesting that she is willing to say, why should she get immunity for her alleged crimes? She'll take the blame and at no cost to her due to her immunity.  She could claim she was responsible for everything as far as she could remember and walk free unless perjury could be proven later. Perjury is very difficult to prove. Think Bill Clinton lying under oath about sex for a reference. I doubt Lerner will ever roll over on her bosses in the IRS and White House unless a special prosecutor is closing in on her and jail time is a real possibility. That isn't a likely scenario as long as Eric Holder is Attorney General and Lois Lerner knows that fact.