Advanced Topics in Genetics Microchimerism Major reference: J.L. Nelson, “Your Cells Are My...
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Transcript of Advanced Topics in Genetics Microchimerism Major reference: J.L. Nelson, “Your Cells Are My...
Advanced Topics in Genetics
MicrochimerismMajor reference: J.L. Nelson, “Your Cells Are My Cells,”
Scientific American, Feb. 2008
Advanced Topics in Genetics: Micochimerism
• Definition: a situation in which an individual has a small number of cells that arose from a different individual• These cells are genetically distinct
from the host.
Micochimerism• The most common type arises during
pregnancy.• A few cells can cross from the mother to
the fetus, and from the fetus to the mother. (When did we hear about this before?)
• If these are stem cells, they may be able to grow and persist in the other individual.
Detection of Micochimerism
• Microchimerism is most obvious when the sexes of the individuals differ
• What would be an obvious microscopic difference for female cells in a male?
• For male cells in a female?
Micochimerism
• Another type arises from organ transplant or blood donation.• The donated tissue may contain
stem cells that migrate to another part of the recipient body and reproduce.
Micochimerism
• A third type arises from exchange of cells between twins.• There may also be cells obtained from
a “vanished twin” that was lost early in pregnancy.• Some evidence for transfer from
mother to child during breast feeding.
Micochimerism: How Much?
• Some studies suggest we all contain some microchimeric cells from our mothers.• All mothers may have some
microchimeric cells from their children.• May amount to about 1 in 1000 cells.
Micochimerism: Role in Disease
• Because they may have some distinct antigens, microchimeric cells might be attacked by the immune system.• This could lead to damage of the
person’s tissues.• Autoimmune disease – a disease in
which the person’s immune system attacks his or her own tissues.
Micochimerism: Role in Disease
• There is evidence that microchimerism is involved in at least some cases of these autoimmune diseases:–Scleroderma (results in thickening of
skin and other damage)–Systemic lupus erythematosus (many
organs are attacked)