Superantigens are presented by and activate thymocytes from infants.

TY - JOUR

T1 - Superantigens are presented by and activate thymocytes from infants.

AU - Thulesen, S

AU - Jørgensen, A

AU - Gerwien, J

AU - Dohlsten, M

AU - Holst Nissen, M

AU - Ødum, Niels

AU - Röpke, C

N1 - Keywords: Antigen Presentation; Antigen-Presenting Cells; Antigens, CD; Apoptosis; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cells, Cultured; Child, Preschool; Epithelial Cells; Flow Cytometry; HLA-DR Antigens; Humans; Infant; Infant, Newborn; Superantigens; T-Lymphocytes; Thymus Gland

PY - 1999

Y1 - 1999

N2 - A high percentage of human fetal and postnatal thymocytes express MHC class II molecules. This raises the possibility that human thymocytes in early life are able to present peptides to other immature T cells and thereby initiate thymic selection of these cells. Here we address this question by exposing newly harvested infant thymocytes to superantigen (Sag) which binds to the T-cell receptor and to MHC class II chains outside the peptide binding groove. The results show that the thymocytes are able to present Sag and to be activated to proliferation as well as apoptosis by Sag presented by other thymocytes. The absence of responses to Sag with mutations in class II binding sites showed that class II molecules were necessary for the responses, and very low expression of class II molecules on CD4-8- cells indicates that the demonstrated T-cell/T-cell interactions are confined to T-cell receptor-positive CD4+8+, CD4+8-, and CD4-8+ cells. These latter subsets were shown to be able to present Sag to each other. These findings suggest that class II+ thymocytes may participate in the selection of self-restricted T cells during a critical period in the shaping of the human immune system. Copyright Copyright 1999 S. Karger AG, Basel

AB - A high percentage of human fetal and postnatal thymocytes express MHC class II molecules. This raises the possibility that human thymocytes in early life are able to present peptides to other immature T cells and thereby initiate thymic selection of these cells. Here we address this question by exposing newly harvested infant thymocytes to superantigen (Sag) which binds to the T-cell receptor and to MHC class II chains outside the peptide binding groove. The results show that the thymocytes are able to present Sag and to be activated to proliferation as well as apoptosis by Sag presented by other thymocytes. The absence of responses to Sag with mutations in class II binding sites showed that class II molecules were necessary for the responses, and very low expression of class II molecules on CD4-8- cells indicates that the demonstrated T-cell/T-cell interactions are confined to T-cell receptor-positive CD4+8+, CD4+8-, and CD4-8+ cells. These latter subsets were shown to be able to present Sag to each other. These findings suggest that class II+ thymocytes may participate in the selection of self-restricted T cells during a critical period in the shaping of the human immune system. Copyright Copyright 1999 S. Karger AG, Basel

M3 - Journal article

C2 - 10575276

SN - 0254-9670

VL - 16

SP - 226

EP - 233

JO - Experimental and Clinical Immunogenetics

JF - Experimental and Clinical Immunogenetics

IS - 4

ER -