Serum interleukin-15 is elevated in systemic lupus erythematosus.
OBJECTIVE
To investigate if interleukin-15 (IL-15) (rather than IL-2) is increased in systemic lupus erythematosus (SLE) and might be responsible for immunological abnormalities of SLE such as the increased lymphocytic expression of Bcl-2 and CD25.


METHODS
Serum IL-15, IL-2 and tumour necrosis factor (TNF) levels of 65 SLE patients, 20 healthy persons and 10 rheumatoid arthritis (RA) patients were measured by enzyme-linked immunosorbent assay (ELISA). For 25 SLE patients, the percentage of CD25 + lymphocytes and the lymphocytic Bcl-2 levels were simultaneously determined by fluorocytometry. Peripheral blood mononuclear cells (PBMC) of 15 SLE patients were incubated with or without recombinant IL-15 and the influence on Bcl-2 and CD25 was determined.


RESULTS
IL-15 was found to be elevated in 25 SLE sera (38%), but in none of the 20 healthy sera (P = 0.0005) and none of the 10 RA sera. Both lymphocyte CD25 and Bcl-2 expression significantly correlated with serum IL-15 and were increased by recombinant IL-15.


CONCLUSIONS
Serum IL-15 may in part be responsible for the immunological abnormalities seen in active SLE.
Aringer
M
M
Department of Rheumatology, Internal Medicine III, University of Vienna, Austria.
Stummvoll
G H
GH
Steiner
G
G
Köller
M
M
Steiner
C W
CW
Höfler
E
E
Hiesberger
H
H
Smolen
J S
JS
Graninger
W B
WB
D000328:Adult; D001172:Arthritis, Rheumatoid / Q000276:immunology; D005260:Female; D006801:Humans; D019409:Interleukin-15 / Q000097:blood*; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D015375:Receptors, Interleukin-2 / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
D019409:Interleukin-15; D019253:Proto-Oncogene Proteins c-bcl-2; D015375:Receptors, Interleukin-2; D014409:Tumor Necrosis Factor-alpha