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In normal humoral immunity, dendritic cells present antigens to the Th cells by arriving at the Lymph node. This is fine. But consider a tumor cell. How does the Tc cell sitting in the lymph node know that there is problem out there? Consider there is a single cell which has undergone mutations and is expressing altered proteins. This wouldn't cause much inflammation to attract the Tc cell there.

So, is there continuous surveillance by the Tc cells? Where exactly do the Tc cells reside? Do they roam around like Th cells? How about the NK cells? do they too roam around in the tissues?

Cases of viral and intracellular pathogens, there may be some inflammation which draws the Tc cells there. Maybe. This can not be in tumors. So how do the Tc cells reach there?

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  • $\begingroup$ T cells are not only present in the circulation, they are also present in the tissues. $\endgroup$ – Chris Mar 3 '16 at 19:47
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    $\begingroup$ I'd read through Trafficking of T Cells into Tumors. $\endgroup$ – CKM Mar 3 '16 at 20:48
  • $\begingroup$ Depending on tumor type, there can be plenty of inflammation inside it. $\endgroup$ – MattDMo Mar 3 '16 at 21:19
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I do not remember enough details to share a mechanistic insight.

However, chemotaxis is a likely answer, which basically means moving along concentration gradient of certain ligand of interest.

Also relevant to your question: a hypothesis called 'immune surveillance' gaining support over the past few years.

http://www.biolegend.com/cancerimmunoediting

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  • $\begingroup$ So if immunosurveillance is actually occurring, in the case of humoral immunity, why do the dendritic cells have to travel all the way to the lymph node? If there is surveillance, the Th cells themselves will be at the site. Doesn't movement of both Th and Dendritic cell reduce the probability of contact? $\endgroup$ – Polisetty Mar 4 '16 at 13:54

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