|
Your immune cells recognize major histocompatibility complex proteins(MHC) when
they distinguish between self and non-self. An MHC protein serves as a
recognizable scaffold that presents pieces (peptides) of a foreign protein
(antigenic) to immune cells.
An empty "foreign" MHC scaffold itself can act as an antigen when donor organs
or cells are introduced into a patient's body. These MHC self-marker scaffolds
are also known as a patient's "tissue type" or as human leukocyte antigens
(HLA) when a patient's white blood cells are being characterized.
For example, when the immune system of a patient receiving a kidney transplant
detects a non-self "tissue type," the patient's body may rally its own immune
cells to attack.
Every cell in your body is covered with these MHC self-marker proteins,
and--except for identical twins--individuals carry different sets. MHC marker
proteins are as distinct as blood types and come in two categories--MHC Class I:
humans bear 6 markers out of 200 possible variations; and MHC Class II: humans
display 8 out of about 230 possibilities.
< Previous | Index | Next Slide > |
