Isolation of a lactose-binding protein with monocyte/macrophage chemotactic activity. Biological and physicochemical characteristics.
BACKGROUND
We established a T cell line, STO-5, which constitutively produced monocyte/macrophage chemotactic activity via human T cell lymphoma-leukemia-virus-induced transformation of normal human T cells.


METHODS
We isolated and purified a lactose-binding protein, MCF-pl5-L (MW of about 50 kD, pl of about 5) from a conditioned medium of STO-5. By using highly purified MCF-pl5-L, its biological and physicochemical properties were elucidated in comparison with C5a and MCP-1.


RESULTS
MCF-pl5-L exhibited an evident dose-dependent monocyte chemotactic activity (MCA). MCF-pl5-L had no or little affinity for heparin unlike chemokines such as MCP-1. We further found that MCF-pl5-L exhibited potent chemotactic activity not only for monocytes but also for alveolar macrophages. In contrast, C5a and MCP-1 failed to show evident chemotactic activity for alveolar macrophages though they did show MCA. MCF-pl5-L failed to exhibit evident eosinophil and neutrophil chemotactic activities, indicating its chemotactic activity is selective for monocytes/macrophages. Regarding the biological functions of MCF-pl5-L other than MCA and chemotactic activity for alveolar macrophages, we found that MCF-pl5-L but not C5a and MCP-1 could prolong the life span of alveolar macrophages, probably by inhibiting apoptosis of macrophages, and stimulate the production of TNF-alpha from macrophages.


CONCLUSIONS
These results suggest that MCF-pl5-L plays a role as an immune modulator for monocytes/macrophages in the site.
Yamanaka
T
T
First Department of Internal Medicine, Kumamoto University School of Medicine, Kumamoto, Japan.
Saita
N
N
Kawano
O
O
Matsumoto
M
M
Kohrogi
H
H
Suga
M
M
Ando
M
M
Hirashima
M
M
D002352:Carrier Proteins / Q000302:isolation & purification* / Q000494:pharmacology; D002630:Chemotactic Factors / Q000302:isolation & purification* / Q000494:pharmacology; D002634:Chemotaxis, Leukocyte; D017077:Culture Media, Conditioned; D016207:Cytokines / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D029968:Escherichia coli Proteins; D006801:Humans; D015458:Leukemia, T-Cell / Q000276:immunology; D016399:Lymphoma, T-Cell / Q000276:immunology; D016676:Macrophages, Alveolar / Q000187:drug effects*; D009000:Monocytes / Q000187:drug effects*; D009004:Monosaccharide Transport Proteins; D027981:Symporters; D014407:Tumor Cells, Cultured / Q000276:immunology
D002352:Carrier Proteins; D002630:Chemotactic Factors; D017077:Culture Media, Conditioned; D016207:Cytokines; D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D009004:Monosaccharide Transport Proteins; D027981:Symporters