Scavenger receptors mediate adhesion of activated B lymphocytes.
The scavenger receptor (SR-A) is considered to play a role in host defense by scavenging endotoxins, oxidized proteins, and denatured or otherwise modified self components, which are routed toward degradation in macrophages. Recent data suggest that SR-A also functions as an adhesion molecule. Our previous finding of SR-A expression by high endothelial cells of venules and on follicular dendritic cells in peripheral lymph nodes prompted us to investigate whether SR-A can act as an addressin for lymphocytes. We describe here that activated B cells adhere to CHO cells transfected with either the type I or type II isoform of SR-A. In contrast, resting B cells isolated from peripheral blood did not adhere to SR-A transfected CHO cells. Other types of leukocytes did not bind to SR-A. The adhesive properties of B lymphocytes in different stages of activation were further explored using lymphoma cell lines of the B cell lineage. The in vitro EBV-transformed B cell line IARC171 showed enhanced adhesiveness to SR-A, whereas the Burkitt lymphoma cell lines, BL41, Rael, and Bl16 did not. The SR-A-dependent adhesion of B-lymphoblasts occurred both at 37 and 4 degrees C, suggesting that it was not dependent on cell metabolism. The known polyanionic ligands for SR-A, fucoidan, and acetylated low density lipoprotein, which bind to a positively charged portion of the collagen-like domain of SR-A, did not inhibit adhesion. This finding suggests that SR-A mediates adhesion of activated B lymphocytes through a binding site that differs from the one that binds polyanionic ligands. Together, our data suggest that SR-A plays a role in the recruitment of activated B cells into lymph nodes and inflammatory lesions by acting as an adhesion molecule for such cells.
Yokota
T
T
Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden.
Ehlin-Henriksson
B
B
Hansson
G K
GK
D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000502:physiology*; D002051:Burkitt Lymphoma; D016466:CHO Cells; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D006224:Cricetinae; D005434:Flow Cytometry; D004854:Herpesvirus 4, Human / Q000235:genetics; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology; D008024:Ligands; D008077:Lipoproteins, LDL / Q000097:blood / Q000494:pharmacology; D008213:Lymphocyte Activation; D008565:Membrane Proteins; D009000:Monocytes / Q000502:physiology; D011134:Polysaccharides / Q000494:pharmacology; D011971:Receptors, Immunologic / Q000096:biosynthesis / Q000502:physiology*; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000494:pharmacology; D051117:Scavenger Receptors, Class A; D051122:Scavenger Receptors, Class B; D014162:Transfection; D014407:Tumor Cells, Cultured
D000925:Anticoagulants; D007376:Interleukin-2; D008024:Ligands; D008077:Lipoproteins, LDL; D008565:Membrane Proteins; D011134:Polysaccharides; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D011994:Recombinant Proteins; C454739:Scarb1 protein, mouse; D051117:Scavenger Receptors, Class A; D051122:Scavenger Receptors, Class B; C032629:acetyl-LDL; D015847:Interleukin-4; C007789:fucoidan