Effect of IL15 on T cell clonality in vitro and in the synovial fluid of patients with rheumatoid arthritis.
OBJECTIVE
Recent studies have suggested that interleukin (IL) 15 induces T cell accumulation in synovial lesions of rheumatoid arthritis (RA). This study aimed at determining whether this cytokine could explain in vivo T cell clonality in RA.


METHODS
Peripheral blood mononuclear cells (PBMC) from patients with RA were stimulated in vitro with IL15 or IL2. After isolation of mRNA from stimulated cells and synovial T cells, genes coding the V-D(N)-J (CDR3) region of T cell receptor beta chains were amplified by a reverse transcriptase polymerase chain reaction. A single strand conformation polymorphism analysis was used to detect the clonotype(s) of accumulating T cells. Nucleotide and amino acid sequencing was also performed.


RESULTS
Stimulation of PBMC with IL15 resulted in oligoclonal expansion of T cells. However, IL15 induced clones from PBMC were mostly different from the dominantly expanding T cell clones in synovial fluid. Furthermore, IL15 and IL2 responding clones were only partially identical.


CONCLUSIONS
Although IL15 results in clonal accumulation of T cells, T cell clonality in rheumatoid joints could not be explained by the effect of IL15 alone. The results indicated the requirement of other factor(s), in addition to IL15, in the pathological process affecting RA joints. The results also suggested different responses by each T cell clone to IL15 or IL2.
Masuko-Hongo
K
K
Rheumatology, Immunology and Genetics Program, Institute of Medical Science, St Marianna University, Kawasaki 216-8512, Japan. mas-hongo.kayo@nifty.ne.jp
Kurokawa
M
M
Kobata
T
T
Nishioka
K
K
Kato
T
T
D000368:Aged; D000595:Amino Acid Sequence; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001327:Autoimmune Diseases / Q000276:immunology*; D001483:Base Sequence; D018929:Cell Culture Techniques; D002455:Cell Division / Q000187:drug effects / Q000276:immunology; D002999:Clone Cells / Q000187:drug effects / Q000276:immunology; D005260:Female; D006801:Humans; D019409:Interleukin-15 / Q000276:immunology / Q000494:pharmacology*; D007376:Interleukin-2 / Q000276:immunology; D008213:Lymphocyte Activation; D008875:Middle Aged; D008969:Molecular Sequence Data; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics; D013582:Synovial Fluid / Q000276:immunology*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology
D019409:Interleukin-15; D007376:Interleukin-2; D016693:Receptors, Antigen, T-Cell, alpha-beta