微嵌合體

Also known as chimerism

right|thumb|220px|During pregnancy, a two-way traffic of immune cells may occur through the placenta. Exchanged cells can multiply and establish long-lasting cell lines that are immunologically active even decades after giving birth. Microchimerism is the presence of a small number of cells in an individual that have originated from another individual and are therefore genetically distinct. This phenomenon may be related to certain types of autoimmune diseases although the responsible mechanisms are unclear. The term comes from the prefix "micro" + "chimerism" based on the hybrid Chimera of G