Often, patients who need a kidney transplant have a living donor. 不幸的是，许多活体献血者的血液或组织类型可能与接受者不匹配. 如果供体器官与受体的血液和组织不匹配，移植就会失败. 不相容的供体/患者可能对我们的不相容肾移植项目感兴趣.

In this section:

• Blood Compatibility
• Positive Crossmatch and Sensitized Patient Program
• Paired Kidney Exchange
• Non-Directed Donation

Blood Compatibility

活体移植供者和受者应该有匹配或相容的血型，以减少器官排斥的风险. If you are unsure of your blood type, 您的医生将在您的评估过程中与您一起审查这些信息. Blood type is based on surface antigens on your red blood cells, and are grouped into categories named A, B, AB, or O. Blood type is genetically determined, so it is likely that a close family member shares your blood type.

Positive Crossmatch and Sensitized Patients

About 30% of transplant patients are sensitized. 这意味着它们有有害的抗体，会攻击外来组织, such as the transplanted organ from a living donor. These antibodies develop through a previous exposure to foreign tissue, such as through pregnancy, previous transplants, or blood transfusions. 致敏的患者可能比未致敏的患者等待匹配的已故供体肾脏的时间长三到四倍.

To test a recipient for these antibodies, 他们的血液样本与潜在献血者的血液样本混合. This test is called a “crossmatch,” and shows how a recipient’s antibodies react with the potential donor’s. Test results can be either positive or negative. It may seem confusing at first, 但是阳性交叉配型意味着供体和受体不相容.

交叉配型阳性会导致受体的抗体攻击供体的抗体，这意味着该肾脏不适合移植.

阴性交叉配型意味着受体的抗体不会攻击供体的抗体，这意味着肾脏适合移植.

• Positive Crossmatch:

  交叉配型阳性会导致受体的抗体攻击供体的抗体，这意味着该肾脏不适合移植.

• Negative Crossmatch:

  阴性交叉配型意味着受体的抗体不会攻击供体的抗体，这意味着肾脏适合移植.

如果供体和受体不相容，移植仍然可以进行. 约翰霍普金斯综合移植中心的专家开发了一种方法 plasmapheresis, 哪一种方法能使肾脏与受体更相容，并显著影响生存结果.

Plasmapheresis

人血液中的抗体有助于保护我们的身体免受外来物体的侵害. Typically, your antibodies protect you from viruses and bacteria. However, in the case of an organ transplant, 你的抗体可能会把你的新器官误认为是一个入侵的物体，并试图保护你的身体免受这个入侵者的侵害.

Plasmapheresis is similar to dialysis; however, it removes the plasma portion of the blood where the antibodies are located. Plasma is the almost clear part of the blood which carries red cells, white cells, platelets and other substances through your bloodstream. 在血浆置换过程中，你将需要一个工作的原生瘘管，移植物或透析导管. If you have a catheter, 一根导管连着管子，将血液输送到血浆分离机. A second line of the catheter is used to return the blood. 如果你有瘘管或移植，针将被放置，因为他们是透析. You may feel some minor discomfort when the needles are placed in position. This is similar to what a blood donor experiences.

移植患者可能需要在手术前后进行多次血浆置换以去除抗体. In addition, the patient’s spleen, which produces antibodies, may be removed.

Patients will also require immunosuppressive medication. 这在移植前是必需的，手术后也可能需要.

What is a Paired Kidney Exchange?

Since 2001, 约翰霍普金斯综合移植中心参与了配对肾脏交换. A paired kidney exchange, 也被称为“肾交换”发生在活体肾脏供体与接受者不相容的情况下, and so exchanges kidneys with another donor/recipient pair. Two live donor transplants would occur. 假设有两对供体/受体，供体和受体1以及供体和受体2:

• Donor 1 would give a kidney to Recipient 2.
• Donor 2 would then give a kidney to Recipient 1.

这种肾脏配对捐献移植使两个不相容的受者获得健康, more compatible kidneys. 所有医学上符合条件的供体/受体配对都可以参加配对肾脏交换计划.

In more complex cases, additional donor/recipient pairs may be used. 参加配对肾脏交换计划可以让受赠者获得更匹配的肾脏, 并帮助其他可能继续等待匹配供体的人. 大约45%的供体/受体配对可以通过参加国家配对肾脏交换计划找到完美匹配的供体.

Non-Directed Donation

非定向捐赠者是普通人，他们决定通过捐赠肾脏来改变陌生人的生活. When connected with incompatible, existing donor/recipient pairs, non-directed donors start a domino effect of kidney donations. 非定向捐赠与活体捐赠相结合，可以显著降低等待移植的患者数量.

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