T cells in action

If you haven't been reading iayork's journal, you might want to check out this description of a remarkable talk he attended on how cells in the immune system respond to antigens:

[...] a T cell will respond to an appropriate antigen with a calcium burst. The T cell might do a lot of things after that -- kill the target cell, release interferon, divide, whatever. This calcium burst is apparently very specific -- a closely-related antigen won't trigger this burst. A very closely related antigen won't trigger the calcium burst, but, surprisingly, the T cell responds anyway, in a kind of a negative way: it might actively shut down interferon release, say, or even commit suicide.

Okay. So there's a burst of calcium after exposure to antigen. You can detect that burst in a second or two. What happens before that?

No one knew, because you can't measure the calcium flux on a shorter scale. Except that Mark's collaborator has figured out how to do it on a nanosecond scale, and so Mark showed us movies of single T cells, responding to their antigen, stretching out the first second to last a minute or so.[...]

What they found was unexpected and sounds like it was pretty visually impressive.