Different Pathways Of Allorecognation : Direct, Indirect, And Linked Pathways

Dendritic cells are the antigen presenting cells (APCs). They play a key role in regulating the adaptive immune response. T cells can recognize the antigen only when they are processed and presented in the context of MHC molecules (type I or II) by the professional antigen presenting cells (APCs). DCs are referred to as professional APCs, since their main function is to present antigens, and only DCs have the unique ability to induce primary immune response in the resting naïve T cells which have not experienced the antigen before. DCs capture antigens, process them and present them on the cell surface in a form that T cell can recognize along with appropriate costimulatory molecules essential for effective activation. Other types of APCs include

Patients who underwent this procedure had to remain on immunosuppressive drugs for about 6 months to prevent the recipient’s immune system from destroying the donor cell. One out of seven patients that had this procedure done had a relapse because they stopped taking their immunosuppressant drug during the critical stage of treatment. This treatment has proven successful, but there still remains the concern of tissue rejection and other complication. Nevertheless, this approach still provides encouragement for people suffering with the disease.

Rejection can't be totally avoided; nonetheless, a level of safe resilience to the transplant develops. A few ideas have been proposed to clarify the advancement of halfway resistance. They incorporate clonal erasure and the advancement of anergy in benefactor particular lymphocytes, improvement of silencer lymphocytes, or variables that down-direct the insusceptible reaction against the join. Different speculations incorporate the steadiness of benefactor determined dendritic cells in the beneficiary that advance an immunologically interceded chimeric state between the beneficiary and the transplanted

Another health problem that treatment with embryonic stem cells can cause is tissue rejection. As is the case with current organ transplantation procedures, embryonic stem cells are harvested from many people all who possess a unique set of genes; therefore, the stem cells are not genetically matched for each patient (Herold 48-49). The difference in genetics causes the body to reject the tissue and the immune system begins to attack the transplanted tissue like it would a virus or bacteria in an attempt to remove the perceived threat. To avoid the implanted tissues being rejected by the body, doctors must prescribe immune suppression drugs that must be taken for the remainder of the patient’s life, even with these drugs the tissue may still be rejected and

Does there exist a universal HLA matching? (analogous to type O blood being the universal donor) Or perhaps can antigens be processed to increase compatibility rates in organ donations? These are just a few of the many questions I have accumulated in a notebook I keep hidden under my pillow--simply thinking about these problems has led to many sleepless nights. From a very young age, I’ve always had a keen eye and a curious mind that have motivated me to ask questions about the things around me. My curiosities eventually developed into the dream of being a scientist, which has been

The demand for an organ transplant continues to grow and when an organ becomes available there are multiple precautions to take to make sure the body does not reject the organ. The certain anti-rejection (immunosuppressant) medication that needs to be taken before a transplant to decrease the body’s immune response from attacking a foreign object (the transplant organ). The medication also lowers the immune system. Therefore, the immune system does not cause the body to reject the organ. Statists have shown, that up twenty percent of patients that get an organ transplant, experience one out of the three organ rejections.

are the graft, the patient, the host. Unfortunately, the graft cells can attack the patient.

Individuals having the “weak D” phenotype (Du) have low levels of expression of the D antigen. This phenotype is the result of an amino acid substitution that affects the insertion of the protein into the RBC membrane. However, all epitopes are present, so these individuals are not in danger of antibody formation following transfusion with D-positive blood. In contrast, in persons having the “partial D” phenotype, a hybrid protein that lacks several epitopes is produced. Therefore, if those having the “partial-D” phenotype receive D-positive blood, they may produce an immune response to the missing epitope, causing a transfusion reaction.

Many pathological conditions can be treated through the use of allogeneic transplants. An allogeneic transplant is when cells, tissues, or organs from a donor are placed into a recipient that is genetically different. Because the donor and recipient are not identical, it is possible for the graft to reject, which when there is an immune response against the graft. It is also possible for a more serious complication to occur, known as Graft-versus-host disease. Graft-versus-host disease typically occurs in cases of bone marrow or stem cell transplants, but it can also occur in other cases as well. In this condition, immune cells in the grafted tissue recognize the host body cells as foreign, and attack them. Normally, immune cells do not attack their own body cells due to cell proteins called human leukocyte antigens (HLA). Every person has a different HLA pattern, which makes allogeneic transplants more difficult. For a transplant to be successful,

There are many cases of allogeneic organ transplants being susceptible to rejection by being attacked by the recipient's immune system. Growing an organ from human tissue in another species increases the chances of rejection and might lead to several other complications that have not yet been considered nor are fully understood.

Chronic graft rejection is caused by both antibodies and lymphocyte. In antibody-induced chronic graft rejection, the rejection is through complement fixation which causes coagulation and tissue injury. Complement activation also use macrophages and neutrophils to cause

Chronic rejection: slow and progressive, and usually occurs in transplants that survive the initial rejection phases. Scientists are still unclear about the process, and research in this area is very difficult as xenografts rarely survive past the initial acute rejection phases.

MHC restriction means that T cells can only recognize the Ags that are presented by their own MHC molecules. After an invader enters a cell, it is broken down to an antigen and is brought to the cell to be presented to T cells by the major histocompatibility complex (MHC) class I or class II. When T cells develop, they go through a selection in thymus so that the TCR will not recognize self, meaning that the TCR will not recognize and MHC that is presenting a self-antigen. More in-depth, immature T cells that are found to be able to recognize invaders on self MHCs are kept, but others that will not be of any use or recognize self-antigens will result in programmed cell death. Because a TCR will only recognize certain MHCs and not others, this is the definition of MHC restriction. The MHC restriction comes from the thymus that you were born with rather than genes. This was shown through an experiment with transgenic mice. They showed that the transgenic T cells matured in the thymus and went into the peripheral lymphoid organs. This only occurred if the mouse had the same allelic form of the MHC recognized by the TCR. If the mouse didn’t have the match between MHC and TCR the T cells died in the thymus. This showed that the

Despite continuous opposition towards the advancements, irrefutable evidence suggests that transplants can provide life-changing results and vast improvements in life quality for the people who receive these operations. While undergoing a transplant-based procedure, one does not risk the unsuccess or adverse effects that

Transplantation is a method of treatment for those serious disease patients which could maintain their lives by donating organs. The organs can be transplanted either from a living donors or a dead person. However, every donation should be guaranteed that there is no harm to the health of the donors and agreed by the donors or their families. According to the written parliamentary reply, Datuk Seri Dr S. Subramaniam, the Health Minister of Malaysia said that the donor rate in Malaysia was only one donor per one million citizens while there are 19,000 Malaysians reported waiting for the organ transplant. This is not a good phenomenon because there is a vigorously increase of the number of patients who need transplantation but the increasing rate of organ donors are very slow.