Enhanced intracellular replication of Salmonella enteritidis in HLA-B27-expressing human monocytic cells: dependency on glutamic acid at position 45 in the B pocket of HLA-B27

Arthritis Rheum. 2004 Jul;50(7):2255-63. doi: 10.1002/art.20336.


Objective: To reveal the cause of the impaired elimination of Salmonella enteritidis in HLA-B27-transfected human monocytic cells and to study whether the B pocket of HLA-B27 contributes to these modulatory effects.

Methods: Stable U937 cell transfectants expressing HLA-A2, B27, or different forms of B27 with amino acid substitutions in the B pocket were prepared. Mock-transfected cells were prepared using the antibiotic resistance vector (pSV2neo) alone. Cells were differentiated, infected with S enteritidis, and the number of live intracellular S enteritidis organisms was determined using the colony-forming unit method. To visualize intracellular S enteritidis, the bacteria were transformed with green fluorescent protein (GFP), and studied by confocal microscopy.

Results: Cells expressing wild-type HLA-B27 were more permissive of intracellular replication of S enteritidis compared with mock-transfected or A2-transfected controls. Cells expressing B27 with an altered B pocket composition having either 6 amino acid substitutions (B27.A2B; substitutions H9F, T24A, E45M, I66K, C67V, and K70H) or a single substitution (B27.E45M) were no longer permissive of S enteritidis replication. In contrast, cells expressing B27 with the single substitution of F for H at position 9 (B27.H9F) retained their permissiveness. Studies using GFP-transformed S enteritidis confirmed that the increase in the amount of intracellular bacteria in B27-expressing cells was due to replication of the bacteria.

Conclusion: Our data indicate that HLA-B27 expression modulates the host-microbe interaction that results in an impaired capacity of monocytes to resist intracellular replication of S enteritidis. The phenotype is dependent on glutamic acid at position 45 in the B pocket and, thus, may be due to properties of the B27 heavy chain that are related to this residue. The ability of HLA-B27 to confer susceptibility to Salmonella-triggered reactive arthritis may occur, at least in part, through these modulatory effects.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Cell Line
  • Cell Membrane / metabolism
  • Endoplasmic Reticulum / metabolism
  • Gene Transfer Techniques
  • Green Fluorescent Proteins
  • HLA-B27 Antigen / chemistry
  • HLA-B27 Antigen / genetics
  • HLA-B27 Antigen / metabolism*
  • Histocompatibility Antigens Class I / genetics
  • Histocompatibility Antigens Class I / metabolism
  • Humans
  • Intracellular Membranes / microbiology*
  • Luminescent Proteins / genetics
  • Methionine
  • Monocytes / immunology*
  • Monocytes / microbiology*
  • Phenotype
  • Protein Folding
  • Salmonella Infections / microbiology
  • Salmonella enteritidis / growth & development*
  • Time Factors
  • Transfection


  • HLA-B27 Antigen
  • Histocompatibility Antigens Class I
  • Luminescent Proteins
  • Green Fluorescent Proteins
  • Methionine