Discussion of all aspects of biological molecules, biochemical processes and laboratory procedures in the field.
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Hi, i was wondering if it's possible to use radiation or some process in order to change the surface proteins, CD's, on T-cells. I was particularly thinking of replacing the CD protein from a gamma/delta T-cell, which they are still researching, and putting it on a Cd4 T-cell. Is this possible? If so how would i do it?
You can use radioation only to induce random mutations, and usually to get your desired mutation you cause a thousand non-wanted mutations as a side product.
What CD protein you specifically want to replace? There are dozens of them. Or do you mean replacing the normal alpha/beta T cell receptor with the more rare gamma/delta chains?
In mice you can produce knock-out or genetically engineered T cells, but that is an extremely laborous and costly process.
In theory, you could deliver the gamma/delta genes to a normal alpha/beta CD4+ T cell with a retroviral vector and maybe even silence the alpha/beta genes with siRNA or similar.
For more simple gamma/delta receptor studies you can genetically engineer immortalized T cells (such as Jurkat cells) by transferring the desired genes and then screening for gamma/delta positive cells and cloning them for further studies. That's what we have done in our lab recently.
Ok you answered everything pretty much. but I'm more so wondering if one can move the CD3 protein from a gamma t cell to a Cd4 t cell, and place the CD3 protein on the surface of the CD4 t cell to act as a replacement. This would hopefully make it so that HIV gp120 wouldnt be able to bind to t-cells
Perhaps I'm missing something here, but as far as I know both gamma/delta and "normal" alpha/beta T cells express CD3, so by transferring the CD3 from an A/B cell to a G/D cell makes no difference. Furthermore, I believe both these T cells express CD4 and are suspectible to HIV infection.
Finally, I don't hitnk you can replace CD3 with CD4 or the other way round without losing the functionality of the cell: lack of CD3 makes the T cell receptor non-functional (a prerequisite for many of the fundamental functions of T cells) and lack of CD4 makes A/B T cells non-responsive for antigens offered by antigen-presented cells via their MHC II molecules. It is suggested, though, that G/D cells may function without MHC-recognition, but they may still need CD4 for other functions.
Well I am in high school, and really have no idea what i'm talking about, but im really interested in immunology. so if im wrong, i guess i am. you said that both a/b and d/g t-cells present CD3? i thought that d/g t cells presented CD3 and a/b presented CD4?
The alpha/beta and gamma/delta designations come from the type of chains that form the T cell receptor (TCR). Majority of the T cells have alpha and beta chains in their TCR. CD3 is the co-receptor of the TCR, and thus both a/b and g/d T cells have CD3 expressed with the TCR - without CD3 the TCR is dysfunctional.
CD4 is the co-receptor of TCR that is involved in the recognition of antigens on the surface of the antigen presenting cells (APCs). They are involved in MHC II:peptide recognition, where the peptide is a piece of an antigen the APC has fagosytosed and is displaying to T helper cells (CD4 T cells). Furthermore, this is the target molecule of HIV, just as you mentioned. CD4 is present also in monocytes and macrophages.
The other big subpopulation of T cells is CD8 cells, which in turn recognize MHC I-bound antigens displayed on the surface of body's own cells. Thus they can for example recognize virus infected cells and kill them. Thus they are called cytotoxic T cells, because they are "toxic" to infected cells.
However, the function of g/d T cells is not very well known, and it is possible that they can be actvated without the MHC:peptide recognition involving CD4. That still does not mean that we could replace all our a/b CD4 T helper cells with g/d cells that lack CD4, because a/b CD4 T cells are one of the most crucial components of the adaptive immune system.
CD stands for cluster of differentiation, which indicates a defined subset of cellular surface receptors (epitopes) that identify cell type and stage of differentiation, and which are recognized by antibodies.
There are more than 250 identified clusters, each a different molecule, coating the surface of B lymphocytes and T lymphocytes.
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