Specificity of T-Cell reactions

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Specificity of T-Cell reactions

Post by pdavis68 » Sun May 21, 2006 12:42 pm

Okay, got a somewhat advanced question here...

I'm just starting with immunology and I'm curious about an aspect of T-Cell activation.

As I understand it, naive t-cells are activated (generally in lymph nodes) by antigens brought by APCs (antigen presentation cells). When the t-cells are activated, they clone and differentiate into effector and memory t-cells that express ligands for E and P selectins, among other things. The endothelial cells at the point of infection express E and P selectins and thus this is how the t-cells home in on their target.

Now, t-cells are specific to antigens, so different t-cells respond to different antigens. So what happens in the case where you have two infections at two different locations at the same time?

In both cases, t-cells are activated and endothelial cells at both locations will express E and P selectins. So how do the t-cells specific to the antigens from the infections find the proper target? In other words, let's call the two locations of infection, X and Y. How do the t-cells activated for infection X end up at X and the ones activated for infection Y end up at Y and not vica-versa?



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