VLR-based adaptive immunity.
Lampreys and hagfish are primitive jawless vertebrates capable of mounting specific immune responses. Lampreys possess different types of lymphocytes, akin to T and B cells of jawed vertebrates, that clonally express somatically diversified antigen receptors termed variable lymphocyte receptors (VLRs), which are composed of tandem arrays of leucine-rich repeats. The VLRs appear to be diversified by a gene conversion mechanism involving lineage-specific cytosine deaminases. VLRA is expressed on the surface of T-like lymphocytes; B-like lymphocytes express and secrete VLRB as a multivalent protein. VLRC is expressed by a distinct lymphocyte lineage. VLRA-expressing cells appear to develop in a thymus-like tissue at the tip of gill filaments, and VLRB-expressing cells develop in hematopoietic tissues. Reciprocal expression patterns of evolutionarily conserved interleukins and chemokines possibly underlie cell-cell interactions during an immune response. The discovery of VLRs in agnathans illuminates the origins of adaptive immunity in early vertebrates.
Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany. boehm@immunbio.mpg.de
Thomas
T
Boehm
Nathanael
N
McCurley
Yoichi
Y
Sutoh
Michael
M
Schorpp
Masanori
M
Kasahara
Max D
MD
Cooper
D056704:Adaptive Immunity; D000818:Animals; D000941:Antigens / Q000276:immunology / Q000378:metabolism; D005075:Biological Evolution; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D019070:Cell Lineage / Q000235:genetics / Q000276:immunology; D043525:Cytosine Deaminase / Q000235:genetics; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D008214:Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding / Q000276:immunology; D011487:Protein Conformation; D011946:Receptors, Antigen / Q000737:chemistry / Q000235:genetics / Q000276:immunology*
D000941:Antigens; D011946:Receptors, Antigen; D043525:Cytosine Deaminase