Sooner or later they will kill them. Since monocytes give rise to a variety of macrophages (with more reperatory or stimulatory capacities) it strongly is influenced by your culture conditions and stimulations. In vivo CD8+T-cells need CD4+ T cell help. Especially when they r antigen inexperienced. I don't know what kind of cd8+t-cells you'll use.
Meybe you'll need a restimulation (after 1 week e.g.) and the addition of cytokines like IL-2 and/or IL-15 to see a strong and potent killing. I'm no real expert, though
I got some experiences with dendritic cells derived from monocytes and CD8+T-cells in vitro.
Hope this helps
Regards
Robert
The proportion of T-cells reactive against that specific HLA is going to be very small. As Robert said, you would have to undergo a complete in-vitro antigen-dependent expansion process, in order to grow the alloreactive compartment up to a meaningful proportion of the total T-cell pool. It's very difficult to do this on purpose, and certainly takes a long time. If you see your monocytes dying in the short run, it's probably due to a different mechanism.
Thank you. for your input. I would add that these T cells are specific for a certain HLA-restricted antigen and have been expanded in cultture for at least 2 weeks to enrich the population for CD8+ T cells. Would such an expansion protocol sufficiently generate T cells that are capable of an allogenic reaction against HLA-mismatched monocytes? If not, could you comment on what alternative mechanism is responsible for this observed "allogenic rejection" of monocytes? Thanks in advance.
Now I'm a little confused. Do you have already CD8+ T Cells primed for this specific HLA subtype? (primary and or restimulation!?) if so, they should kill your monocytes really fast, in my opinion.
The CD8+ T cells are primed for a specific MHC Class complex (consisting of a specific peptide). This complex is presented by a target cell line - that is not the monocyte. The monocyte is a third cell type that is artificially added to the 3-cell co-culture. The objective is to investigate the effect of monocytes on the interaction between the primed CD8+ T cells and the MHC:peptide-presenting target cell line (where TCR binding is peptide specific and restricted to that particular MHC Class). I observed that the effect seen with autologous monocytes was, instead, more short-lived when we used allogenic monocytes. Does this clarify? Please let me know where I can further clarify. Thanks Robert!
I think I understand your set up and design now.
Normally, your monocytes/macrophages shouldn't be affected by your antigen primed CD8+T-Cells (besides your monos express the matching MHC-peptide complex too, of course). At least in my understanding.
What in in vitro cultures can happen is the following: If you prime CD8+Tcells on antigens and you use cytokines to push their proliferation, you can also push bystander responses which are more or less antigen unspecific but rather caused by your cytokines. If you now put allogenic MHC expressing cells in your culture, your cytokine treated CD8+Tcells might react much more aggressive even if they have just a weak TCR-MHC-Peptide Affinity. Then you ll see differences betweeen allo- and syngenic monocytes.
This is one possible mechanism in my humble opinion.
Hope this helps. I'm glad to further discuss upcoming questions.
Regards
Robert
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