TIA-1 regulates the production of tumor necrosis factor alpha in macrophages, but not in lymphocytes.
OBJECTIVE
To determine whether TIA-1 differentially regulates the production of tumor necrosis factor a (TNFalphalpha) in macrophages and lymphocytes.


METHODS
Peritoneal macrophages derived from wild-type and TIA-1-/- mice were cultured in the absence or presence of lipopolysaccharide (LPS) before comparison of the production of TNFalpha protein by intracellular flow cytometry and the secretion of TNFalpha protein by enzyme-linked immunosorbent assay. In parallel experiments, splenocytes were cultured in the absence or presence of concanavalin A (Con A), phorbol myristate acetate (PMA)/ionomycin, or anti-CD3/anti-CD28 before comparing the production of TNFalpha protein. Finally, the relative expression of TIA-1 protein in macrophages and splenocytes was compared using immunoblotting analysis.


RESULTS
LPS-activated peritoneal macrophages derived from TIA-1-/- mice produced significantly more TNFalpha than macrophages from wild-type controls. In contrast, splenic lymphocytes (CD3+, CD4+, or CD8+) derived from wild-type and TIA-1-/- mice produced similar amounts of TNFalpha in response to Con A, PMA/ionomycin, or anti-CD3/anti-CD28. Lymphocytes and macrophages expressed similar amounts of TIA-1 protein, indicating that differential expression of TIA-1 cannot account for these results.


CONCLUSIONS
TIA-1 is the target of a regulatory pathway that operates in activated macrophages, but not in activated lymphocytes. Developing drugs that target this pathway might prevent the pathologic overexpression of TNFalpha without subverting the T lymphocyte response to microbial pathogens.
Saito
K
K
Division of Rheumatology and Immunology, Brigham and Women's Hospital, Boston, MA 02115, USA.
Chen
S
S
Piecyk
M
M
Anderson
P
P
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D018106:CD28 Antigens / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology; D002273:Carcinogens / Q000494:pharmacology; D003208:Concanavalin A / Q000494:pharmacology; D005260:Female; D005434:Flow Cytometry; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D011506:Proteins; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D000074019:T-Cell Intracellular Antigen-1; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
D000906:Antibodies; D018106:CD28 Antigens; D017252:CD3 Complex; D002273:Carcinogens; D007476:Ionophores; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D011506:Proteins; D016601:RNA-Binding Proteins; D000074019:T-Cell Intracellular Antigen-1; C499367:Tia1 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D003208:Concanavalin A; D015759:Ionomycin; D013755:Tetradecanoylphorbol Acetate