The identification of lymphocyte-like cells and lymphoid-related genes in amphioxus indicates the twilight for the emergence of adaptive immune system.
To seek evidence of a primitive adaptive immune system (AIS) before vertebrate, we examined whether lymphocytes or lymphocyte-like cells and the related molecules participating in the lymphocyte function existed in amphioxus. Anatomical analysis by electron microscopy revealed the presence of lymphocyte-like cells in gills, and these cells underwent morphological changes in response to microbial pathogens that are reminiscent of those of mammalian lymphocytes executing immune response to microbial challenge. In addition, a systematic comparative analysis of our cDNA database of amphioxus identified a large number of genes whose vertebrate counterparts are involved in lymphocyte function. Among these genes, several genes were found to be expressed in the vicinity of the lymphocyte-like cells by in situ hybridization and up-regulated after exposure to microbial pathogens. Our findings in the amphioxus indicate the twilight for the emergence of AIS before the invertebrate-vertebrate transition during evolution.
Huang
Gonghua
G
State Key Laboratory of Biocontrol, The Open Laboratory for Marine Functional Genomics of State High-Tech Development Program, College of Life Sciences, Sun Yat-sen University, Guangzhou, China.
Xie
Xiaojin
X
Han
Yan
Y
Fan
Lifei
L
Chen
Jie
J
Mou
Chunyan
C
Guo
Lei
L
Liu
Hui
H
Zhang
Qinfen
Q
Chen
Shangwu
S
Dong
Meiling
M
Liu
Jianzhong
J
Xu
Anlong
A
D056704:Adaptive Immunity / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D002816:Chordata, Nonvertebrate / Q000166:cytology / Q000235:genetics / Q000276:immunology*; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000235:genetics; D020224:Expressed Sequence Tags; D005786:Gene Expression Regulation / Q000276:immunology; D005802:Genes, MHC Class II; D005880:Gills / Q000166:cytology; D018257:Helix-Loop-Helix Motifs / Q000235:genetics; D008214:Lymphocytes / Q000276:immunology*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015854:Up-Regulation
D018076:DNA, Complementary; D012333:RNA, Messenger