immuno- S3: transplantation and stem cells

transfer of living cells, tissues, or organs, from one part of the body to another or from one individual to another

what is a transplant/graft?

the sequence of events that occurs after an allograft or xenograft is transplanted into a recipient

what is transplantation immunology?

because of the immune response

why is the success of transplants limited?

a graft from one part of the body to another on the same individual

what is an autograft?

a graft between genetically identical individuals

what is an isograft?

a graft between genetically different individuals of the same species

what is an allograft?

a graft between members of different species

what is a xenograft?

allograft

which is the most common- autograft, isograft, allograft, xenograft?

xenograft

which is the most commonly rejected- autograft, isograft, allograft, or xenograft?

autografting

what is the name for the transfer of self tissue from one body site to another on the same individual?

skin grafts, hair transplants, etc

what are the uses of autografting?

the immune system does not respond

why is there no/less risk in an autograft?

xenografting

what is the name for the transfer of tissue from one species to another?

APCs- dendritic cells, macrophages, B cells

B cells and antibodies

T cells

NK cells

MHC

what components are involved in graft rejection?

an immune response to nonself antigens from members of the same species- alloantigens

what is alloimmunity?

MHC/polymorphic genes inherited from parents

what component of the immune system differentiates self and foreign cells?

Human Leukocyte Antigen (HLA)

human MHC I and II are also called...

both

do alloantigens elicit a humoral or cell mediated response?

genes encoding the proteins or other molecules that are responsible for rejection

what are histocompatibility antigens?

histocompatibility antigens

which genes encode the proteins or other molecules that are responsible for rejection?

the set of alleles present in each chromosome, inherited from both parents and codominantly expressed

what is the MHC haplotype?

T cells

with transplantation, foreign MCH molecules can directly activate______

the donor lymphocytes attack the graft recipient

graft vs host rejection occurs when....

CD4 and CD8 T cells recognize the structure of an intact MCH molecule on APCs

what is direct presentation of alloantigens?

the donor MHC is processes and presented by the recipient APC to CD4 T cells

what is indirect presentation of alloantigens?

removing the thymus

-proves that T cells are crucial in rejection

what surgery is done in experimental animals in order to make them unable to reject a transplant?

a rejection to an allograft

takes minutes to hours

due to anti-donor antibody and complement

what is a hyperacute rejection?

a rejection to an allograft

takes days to weeks

due to primary activation of T cells

what is an acute rejection?

a rejection to an allograft

takes months to years

unclear cause

what is a chronic rejection?

thrombatic occlusion of the graft

preexisting antibodies in host bind to donor endothelial antigens and activate complement

what happens during a hyperacute rejection?

vascular and parenchymal injury/destruction mediated by T cells and antibodies

what happens during an acute rejection?

solid organ transplants

chronic rejection occurs the most in response to what grafts?

blood transfusion

what is the most common tissue/organ transplantation?

O

which blood type can be donated to any blood type?

AB

which blood type can accept any blood tranfusion?

leukemia, anemia, immunodeficiency (especially SCID)

bone marrow transplants are common to treat what?

GVHD- graft versus host disease

because the donor bone marrow is composed of immunocompetent cells

T cells of donor marrow vs alloantigens of the host

bone marrow transplants commonly cause what disease?

precursor cells that are able to renew themselves through mitotic cell division and differentiate into a diverse range of specialized cell types

what are stem cells?

totipotent- can make adult tissues and extraembryonic structures; can divide until it creates a whole organism

pluripotent- can make inner cell mass; can divide into most cell types; cannot make complete organism

what is the difference between totipotent and pluripotent stem cells?

the patient is completely irradiated so all of their cells die before transplantation

for bone marrow transplants, what must be done to the patient?

hematopoietic stem cells

what are the stem cells of blood?

the patient's own blood cells are extracted and filtered to remove the affected cells, and then the healthy cells are reintroduced

how is autotransplantation used for cancer?

they are rich in multipotent hematopoietic stem cells

used for leukemia, anemia

why are umbilical cord step cells used ?

to create fat and growth of blood vessels

what are adipose stem cells used for?

less, they stop proliferating at some point

do pluripotent stem cells have more or less proliferating ability than other stem cells?

-can be grown indefinitely

-can become any body cell

-less likely to carry mutations

what is beneficial about embryonic stem cells?

-less flexible and versatile

-multipotent, so restricted to tissue of origin

-more likely to carry mutations

why are adult stem cells maybe not as efficient as embryonic stem cells?

embryonic- adult stem cells are taken from the patient

which- embryonic or adult stem cells- are at risk of rejection?

-placenta is a barrier and filter- it filters anti-MHC antibodies

-trophoblast- outer layer of fetal tissue (in contact with mother blood) does not have MHC

-placenta secretes neurokinin B with phosphocholine molecules

-fetus has lymphocyte suppressor cells to inhibit maternal cytotoxic T cells

why is a fetus not rejected by the mother?

IgG- protects fetus against infections without targeting it

what antibodies can pass through the placenta, from mother to fetus?

no, only IgG can

can IgM pass through the placenta?