And once the complex forms, it elicits some type of response that begins a defensive mechanism to kill off that particular pathogen. Now, what type of mechanism do we actually have? Well, we have three important types of mechanisms that we're going to focus on in this lecture. Let's begin with mechanism number one. So in this case, what happens is when we form when our antibody binds onto the antigen, it basically inactivates that antigen. So let's take a look at the following case.