Effect of cognate human CD4+ T cell and endothelial cell interactions upon chemokine production.
BACKGROUND
In vitro studies have shown that cognate recognition of antigen presented by endothelial cells (EC) causes T cell activation, proliferation, and cytokine release and alters the transmigration of T cells. Here we have investigated chemokine induction caused by cognate interactions between human CD4+ T cells and MHC class II-expressing EC.


METHODS
HLA-DR-restricted CD4+ T cells were cocultured with HLA-DR-expressing allogeneic Eahy.926, aortic, or heart microvascular EC. Chemokine mRNA expression was measured by RTPCR, and chemokine protein secreted was measured by a cytokine array system and ELISA. Molecules involved in chemokine secretion were identified using blocking monoclonal antibodies, and cellular sources of chemokines determined by intracellular chemokine staining. Coculture supernatants were also used in chemotaxis assays.


RESULTS
Nine different chemokine mRNA and proteins were expressed because of noncognate interactions between T cells and EC. Cognate interactions induced de novo expression of four chemokines and upregulation of seven chemokines. Levels of CCL3, CCL8, and CXCL10 secreted into supernatants were in the nanomolar range and were chemotactic for T cells and monocytes. Blocking antibodies to HLA-DR and LFA-3 abrogated production of CCL3, CCL8, and CXCL10. Blocking antibodies to interferon-gamma and tumor necrosis factor-alpha inhibited CCL8 and CXCL10 but not CCL3 production. CCL3 and CXCL10 were produced by both T cells and EC.


CONCLUSIONS
Cognate interactions between alloreactive CD4+ T cells and MHC class II-expressing EC results in a specific pattern of chemokine production. These chemokines could play important roles in recruitment of leukocytes into vascularised allografts.
Department of Transplant Immunology, National Heart and Lung Institute, Imperial College Faculty of Medicine, Heart Science Centre, Harefield Hospital, Harefield, Middlesex, United Kingdom.
Szun S
SS
Tay
Ann
A
McCormack
Marlene L
ML
Rose
D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D002450:Cell Communication; D054357:Chemokine CXCL10; D019742:Chemokines, CC / Q000096:biosynthesis* / Q000235:genetics; D019743:Chemokines, CXC / Q000032:analysis / Q000096:biosynthesis*; D018920:Coculture Techniques; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D012333:RNA, Messenger / Q000032:analysis
C114753:CXCL10 protein, human; D054357:Chemokine CXCL10; D019742:Chemokines, CC; D019743:Chemokines, CXC; D012333:RNA, Messenger