LFA-1 integrin redistribution during T-cell hybridoma invasion of hepatocyte cultures and manganese-induced adhesion to ICAM-1.
We have reported previously that the integrin LFA-1 is essential for metastasis of T-cell hybridomas to the liver. We show here that hepatocytes isolated from normal non-inflamed rat liver express intercellular adhesion molecule-1 (ICAM-1) at the dorsal surface and more prominently at the lateral and substratum-adherent surfaces. Anti-rat ICAM-1 mAb inhibited adhesion of TAM8C4 T-cell hybridoma cells to hepatocytes. Invasion between hepatocytes was not affected, but this is probably due to lack of penetration of the mAb between the hepatocytes. In all hepatocyte-adherent TAM8C4 cells, LFA-1 was concentrated at the adhesion site. Redistribution of ICAM-1 to the interacting hepatocyte membrane was also seen, but only for part of the adherent TAM8C4 cells. LFA-1 was highly concentrated on pseudopods of invading TAM8C4 cells inserted between hepatocytes, and on the upper surface of invaded TAM8C4 cells located under the hepatocytes. ICAM-1 was concentrated in the hepatocyte membrane overlying TAM8C4 cells located underneath the monolayer. These results suggests that ICAM-1 is of major importance for liver invasion by these lymphoma cells. For optimal adhesion to ICAM-1, LFA-1 on T-cell hybridomas requires activation, which apparently occurs upon contact with cell layers that are invaded (G. La Rivière et al., J. Cell Sci. 107, 551-559, 1994). LFA-1 can be activated artificially by Mn2+. To study LFA-1 redistribution upon ICAM-1 interaction with higher resolution, we performed immuno-EM on cells before and after Mn(2+)-induced adhesion and spreading on immobilized ICAM-1. By immune fluorescence, LFA-1 was observed to redistribute to the ICAM-1-adherent surface, and to be concentrated in lamellipodia of spreading TAM8C4 cells. By immuno-EM, LFA-1 was localized in microclusters of approximately 10 gold particles. This was seen in cells fixed in suspension, and the size of these clusters did not change upon adhesion to ICAM-1. LFA-1 was present at high density in thin filopodia, but again in microclusters of similar size. Comparable results were obtained with a cytotoxic T-cell clone. We conclude that Mn(2+)-induced activation of LFA-1 is not associated with the formation or enlargement of LFA-1 clusters.
Meijne
A M
AM
Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam.
Driessens
M H
MH
La Rivière
G
G
Casey
D
D
Feltkamp
C A
CA
Roos
E
E
D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects; D002459:Cell Fusion; D002478:Cells, Cultured; D006825:Hybridomas / Q000473:pathology*; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D008099:Liver / Q000166:cytology*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism* / Q000502:physiology; D016399:Lymphoma, T-Cell / Q000473:pathology; D008345:Manganese / Q000494:pharmacology*; D016253:Microscopy, Immunoelectron; D009361:Neoplasm Invasiveness; D009363:Neoplasm Proteins / Q000502:physiology; D051381:Rats; D013601:T-Lymphocytes / Q000473:pathology*; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology
D016169:Lymphocyte Function-Associated Antigen-1; D009363:Neoplasm Proteins; D018799:Intercellular Adhesion Molecule-1; D008345:Manganese