The Department of Justice has granted "immunity"to a former State Department employee who worked on Hillary Clinton's private email server. Bryan Pagliano initially invoked his Fifth Amendment right against self-incrimination and would not testify. Of course, the Department of Justice, known to defense attorneys simply as the "government," has many ways of getting people to talk.
The big question is whether there is a grand jury convened. The smart bet is yes. After all, the fact that there are immunity agreements logically means there's a grand jury investigation in some district. The grand jury is typically the genesis of the government's subpoena power. The next, bigger question, is whether anyone will be indicted.
While Pagliano is surely in an unenviable, nail-biting position, we can draw some inferences from recent events. Whether he had zero potential liability, or some liability, he's probably not a "target." Why? Because if he were, his attorney would probably not let him talk to the government, and the government would probably not give him immunity. Remember, the government is parsimonious with immunity deals. Another, less reliable inference may be drawn not about Pagliano, but others who are not Pagliano.
The person who often has to worry the most during this process is the person who hasn't been approached at all by the government. That's a chilling indicator that you may be the target.