Immunology of transplantation and pregnancy Flashcards Preview

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Flashcards in Immunology of transplantation and pregnancy Deck (11):

Transplantation (Def.)

surgical manipulaton of moving cells, tissues and/or organs from one body to another to replace damaged or absent organs and or/tissues


Word for transplantation ...
- within same person
- within two subjects of same species
- between different species:

within same person: autograft
within two subjects of same species: allograft
between different species: xenografts


Medawars 2 basic principles of transplantation:

1. Graft rejection is due to genetic incompability between donor and recipient
2. the mechanism of rejection is immune


Host vs graft reaction
- graft is recognized / rejected by ...?

The graft is recognized as nonself by:
1. Tc:
- recognize nonself MHC molecules (direct recognition)
- recognize minor histocompatibility antigens (indirect recognition)
2. Antibodies

The graft is rejected by
1. T-cells
2. Lymphokines

! Transplantation immunity is basically cellular!

check scheme!


Immune memory in allograft rejection

There is immune memory in allograft rejection, a new tissue is rejected faster


Graft vs host disease (GVHD)
- Conditions

- recipient and graft are incompatible (missing MHC molecules in graft)
- graft is composed of live immune cells f.ex. bone marrow, lymphocytes
- immune system of recipient is either supressed f.ex through chemotheraphie or less developed


Is GVHD be clinically useful in leukemia patients?

Is GVHD be clinically useful in leukemia patients?
○ leukemia is cancer of white blood cells
○ when transplanting healthy bone marrow, it would attack sick marrow -- very helpful


Bone marrow transplantation
- use
- different types of transplantation

- used to treat some types of cancer
- chemotherapy and radiotherapy destroy Hematopoietic stem cells (HSCs) - patient needs new bone marrow with undifferentiated lymphoid cells

- auto transplantation: prior to standart therapy, in vitro culturing, reinjection
- allo transplantation of bone marrow
allo transplantation of stem cells


Def. Stem cells

- undifferentiated cells within a differentiated tissue
- capacity to renovate and differentiate in all cell types of the tissue of origin


Def Embryonic stemm cell

- undifferentiated pluripotent cell originating from the inner cell mass of the blastocyst
- can differentiate into different specialized cell types


The paradox of pregnancy
- what kind of graft is the embryo technically and why is it nonetheless tolerated?

The embryo is an allograft

still tolerated because:
1. Avoiding antigen recocnition:
- the embryo occupies a place which is defended by a nonimmunogenic tissue barrier, the trophoblast
- outer layer of the placenta, encoded by paternal genes
- is does not express MHC molecules -- prevents antigenic recognition and thus immune response

2. Change in maternal immune response:
- predominance of humoral immunity and inhibition of cellular immunity
- protective effect of MHC-G molecules on trophoblast cells
- production of immune inhibitors
- complement inhibition