Effects of methotrexate on differentiation of monocytes and production of cytokine inhibitors by monocytes

Arthritis Rheum. 1998 Nov;41(11):2032-8. doi: 10.1002/1529-0131(199811)41:11<2032::AID-ART19>3.0.CO;2-J.


Objective: To examine the potential of methotrexate (MTX) to act as a differentiation-stimulating factor for monocytes, which could explain the antiinflammatory properties of this agent in the treatment of rheumatoid arthritis (RA).

Methods: Fluorescence-activated cell sorter analysis was used to measure the changes in antigen expression (CD11b/c, CD16, CD64, CD14, CD68, and CD95) in response to MTX, 1,25-OH-cholecalciferol (1,25-OH-CCF), and granulocyte-macrophage colony-stimulating factor in the human monoblastic leukemia cell line U937, bone marrow mononuclear cells (BMMC), and peripheral blood mononuclear cells (PBMC). Release of interleukin-1beta (IL-1beta), IL-1 receptor antagonist (IL-1Ra), tumor necrosis factor a, and soluble tumor necrosis factor receptors (sTNFR) p55 and p75 during the differentiation in vitro was assessed by immunoassay in the culture supernatants.

Results: MTX alone and in combination with 1,25-OH-CCF markedly stimulated the differentiation of the monocytic U937 cells and simultaneously increased Fas-antigen expression. Differentiation was associated with enhanced IL-1Ra and sTNFR p75 release from U937 cells. MTX had fewer effects on phenotypic differentiation of human BMMC and PBMC, but did stimulate IL-1Ra release and inhibit IL-1beta synthesis in BMMC.

Conclusion: MTX acts as a strong differentiation factor for immature and undifferentiated monocytic cells. Differentiation in vitro is associated with an increase in natural cytokine inhibitor release and a simultaneous down-regulation of IL-1beta. These findings may explain the marked clinical antiinflammatory effects of MTX when used in the treatment of RA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, CD / metabolism
  • Antirheumatic Agents / pharmacology*
  • Biomarkers
  • Bone Marrow Cells / cytology
  • Bone Marrow Cells / drug effects
  • Bone Marrow Cells / immunology
  • Calcitriol / pharmacology
  • Calcium Channel Agonists / pharmacology
  • Cell Differentiation / drug effects
  • Cell Differentiation / immunology
  • Cell Division / drug effects
  • Cell Division / immunology
  • Cytokines / antagonists & inhibitors
  • Cytokines / immunology*
  • Granulocyte-Macrophage Colony-Stimulating Factor / pharmacology
  • Humans
  • Interleukin 1 Receptor Antagonist Protein
  • Interleukin-1 / pharmacology
  • Methotrexate / pharmacology*
  • Monocytes / cytology*
  • Monocytes / drug effects
  • Monocytes / immunology
  • Receptors, Tumor Necrosis Factor / metabolism
  • Receptors, Tumor Necrosis Factor, Type I
  • Receptors, Tumor Necrosis Factor, Type II
  • Sialoglycoproteins / metabolism
  • U937 Cells


  • Antigens, CD
  • Antirheumatic Agents
  • Biomarkers
  • Calcium Channel Agonists
  • Cytokines
  • IL1RN protein, human
  • Interleukin 1 Receptor Antagonist Protein
  • Interleukin-1
  • Receptors, Tumor Necrosis Factor
  • Receptors, Tumor Necrosis Factor, Type I
  • Receptors, Tumor Necrosis Factor, Type II
  • Sialoglycoproteins
  • Granulocyte-Macrophage Colony-Stimulating Factor
  • Calcitriol
  • Methotrexate