As we all know, the antibody in our body is an immunoglobulin, secreted by immune cells, and can be combined with anti-A, which is one of the most important immune substances produced in our body's immune process. So how does the human body produce this specific immunoglobulin? In another word, how to produce antibodies in human being?
This combination is mainly the combination of protein and protein, and this combination mainly comes from relatively weak interactions such as intermolecular forces, hydrophobic interactions, electrostatic interactions, and hydrogen bonding. Obviously, this combination is not a strict match, but the matching of certain structures at a certain position on the protein, the same enzyme (receptor) in the physiological and biochemical can be combined with a variety of molecules is evidence. Back to the immune cells, with an antigen recognition t cell receptor that can also bind to a specific antigen (antigen recognition receptors and antibodies are similar or identical, the subject should also understand, and later do not pay attention to distinguish) as an example, there is a powerful The “additional disorder” process (see Medical Immunology): “The mechanism by which antigen receptor diversity is produced. The T cell bank and B cell bank in the immune system contain all T cell clones and B cells with different specificities, respectively. Cloning, the diversity of antigen receptors (BCR as an example) during lymphocyte development is as follows: diversity caused by combination: including a combination of numerous V-region gene fragments and a combination of light and heavy chains. At V, (D), When the J gene fragment is rearranged, only one of the V, (D), and J gene fragments can be taken separately, and thus a plurality of V region gene fragment combinations can be generated. The diversity caused by the connection: in the rearrangement process, V, ( D), the junction of the J gene fragment can be lost or added a few nucleotides, thereby increasing the diversity of BCR and TCR. The diversity caused by high frequency mutation of somatic cells: the diversity caused by the combination and connection The diversity caused by high frequency mutations in somatic cells occurs on the basis of mature V cells that have completed V gene rearrangement, and only occurs in B cells of the peripheral lymphoid germinal center after antigen stimulation. Somatic cell high frequency mutation is A point mutation. "The human body, as a more sophisticated instrument, deliberately allows certain genes to be fragmented and recombined, and also adds and subtracts nucleotides, and allows high frequency mutations! It is conceivable that if most other somatic cells dare to play like this, there are basically three endings: they finish the egg, get the body out of the egg, and get the eggs done by the immune cells. However, all these purposes are to achieve the diversity of antigen recognition receptors through genetic diversity. That is, the antigen is the diversity of the structure of the receptor protein, and ultimately it is reflected in the function of the diversity of recognition specificity. This diversity is exactly what the subject said in the textbook. "The true meaning." Because of this diversity, it is not easy to find two B cells that produce exactly the same antibodies. To illustrate my understanding of protein interactions, I have made a simplified model design with several examples: (If the subject has an understanding of protein interactions, the "Situation" section later does not need to be looked at.) Putting antibodies and receptors Both are seen as one-dimensional surfaces. Taking electrostatic action as an example, P represents a positively charged region, N represents a negatively charged region, and X represents a region that does not participate in interaction. Then the antibody XXXPXX receptor XXXNXX is clearly that the two can interact. However, we here suggest that the letters take away the equal nature, so the protein is actually divided into equal areas. While proteins are not strictly acting, so assuming that a region X is replaced by a smaller region x, then there are cases 2, and interactions are equally likely to occur. Antibody XXXPXX, receptor XXxNXX or, assuming that the negative electroconductivity of the negative part is reduced, as n, as long as it is not below a certain limit, it is possible to interact with multiple sites of action XXXPXX receptor XXXnXX, which may be only global The image of the overall result, so it is not necessary for each site to accurately correspond, as in case four. There may also be specific locations that make the entire combination impossible, as in case five, there is a special zone Y containing a large group that makes the molecule inaccessible. The antibody XPXXNXXP receptor XNXXXXXN, antibody XXPXXP receptor XXNYXN, in fact, the protein interaction is very complex, coupled with the existence of a metastable conformation in the protein conformation. It makes it difficult to make simple judgments, and many computer software can simulate now. The immune cell surface receptors also play a role in transmitting signals, which is more complicated. I am not studying this aspect, I will not elaborate. In general, there is always an antibody in the body (after all, it took so much effort and recombination and mutation. However, it is still a very computationally intensive work to speculate the structure of the protein through the DNA sequence, which belongs to the "protein structure." The problem of optimization, knowing that there are many wonderful answers), either strong or weak, can interact with antigenic proteins. After all, there are always characteristics of positive, negative, hydrophobic, hydrophilic, hydrogen-bonded ligands, and hydrogen-bonded receptors. There is no match at one position of the antigen and it may match at another position in the antigen. This human antibody production does not match and another antibody may match. When the antigen recognition receptor on the surface of the matched cell binds to the antigen, a series of immunological processes can generate a large amount of immune cells corresponding to the antibody, and generate an immune reaction, such as secreting antibodies and killing target cells. In general, the existence of antibodies is: random mutation, "suitable" amplification.
To put it simply, the VDJ gene is rearranged in the B cell, and if it is determined that it will not accidentally injure the person in the bone marrow, it will be placed in the secondary immune organ. If it is accidentally injured, it will be corrected and no longer changed. Directly shot. In this way, the antibodies that go out will not accidentally injure oneself, and then contact the antigen, the B cells mature, the antibody gene is mutated by the AID enzyme, and then the affinity is increased, the lowering is hanged, and the cycle is repeated... This is the source of the antibody. With the evolutionary process. Antibodies are only available with antigens, and antibody updates also depend on exposure to antigens. The antibodies in your body are no longer regulated by your genes. How can your genes automatically mutate to produce the corresponding antibodies before they come into contact with new antigens? Parents, to be precise, are maternal, and will transfer some of their antibodies to their offspring during pregnancy and breastfeeding to make them spend a period of just production.
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