Developmentally regulated interactions of human thymocytes with different laminin isoforms.
The gene family of heterotrimeric laminin molecules consists of at least 15 naturally occurring isoforms which are formed by five different alpha, three beta and three gamma subunits. The expression pattern of the individual laminin chains in the human thymus was comprehensively analysed in the present study. Whereas laminin isoforms containing the laminin alpha1 chain (e.g. LN-1) were not present in the human thymus, laminin isoforms containing the alpha2 chain (LN-2/4) or the alpha5 chain (LN-10/11) were expressed in the subcapsular epithelium and in thymic blood vessels. Expression of the laminin alpha4 chain seemed to be restricted to endothelial cells of the thymus, whereas the LN-5 isoform containing the alpha3 chain could be detected on medullary thymic epithelial cells and weakly in the subcapsular epithelium. As revealed by cell attachment assays, early CD4- CD8- thymocytes which are localized in the thymus beneath the subcapsular epithelium adhered strongly to LN-10/11, but not to LN-1, LN-2/4 or LN-5. Adhesion of these thymocytes to LN-10/11 was mediated by the integrin alpha6beta1. During further development, the cortically localized CD4+ CD8+ thymocytes have lost the capacity to adhere to laminin-10/11. Neither do these cells adhere to any other laminin isoform tested. However, the more differentiated single positive CD8+ thymocytes which were mainly found in the medulla were able to bind to LN-5 which is expressed by medullary epithelial cells. Interactions of CD8+ thymocytes with LN-5 were integrin alpha6beta4-dependent. These results show that interactions of developing human thymocytes with different laminin isoforms are spatially and developmentally regulated.
Kutlesa
Snjezana
S
University Medical Clinic, Section for Transplantation Immunology and Immunohematology, ZMF (Center for Medical Research), Waldhōrnlestrasse 22, 72072 Tübingen, Germany.
Siler
Ulrich
U
Speiser
Angelika
A
Wessels
Johannes T
JT
Virtanen
Ismo
I
Rousselle
Patricia
P
Sorokin
Lydia M
LM
Müller
Claudia A
CA
Klein
Gerd
G
D015496:CD4-Positive T-Lymphocytes / Q000502:physiology; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology; D002448:Cell Adhesion; D002454:Cell Differentiation; D004727:Endothelium / Q000737:chemistry; D004848:Epithelium / Q000737:chemistry; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry / Q000379:methods; D007223:Infant; D016023:Integrins / Q000502:physiology; D007797:Laminin / Q000032:analysis*; D019030:Receptors, Vitronectin; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000502:physiology*; D013950:Thymus Gland / Q000098:blood supply / Q000737:chemistry*
D016023:Integrins; D007797:Laminin; D019030:Receptors, Vitronectin; C094340:integrin alphavbeta1; C119013:laminin 10; C102645:laminin alpha 2; C097043:laminin alpha5