Dual inhibitory and stimulatory activities in serum from SLE patients and lupus mice that regulate the proliferation of an IL-2-dependent T cell line.
In serum and plasma from SLE patients, we have detected elevated levels of factors which regulate proliferative responses of CTLL cells to IL-2. Serum samples containing these factors have dose-dependent dual inhibitory and stimulatory activities on the proliferation of this IL-2-dependent T lymphocyte cell line. At high concentrations, the serum factors inhibit the proliferative responses of CTLL cells to IL-2. At low concentrations, they synergise with IL-2 stimulating the growth of cells. Similar inhibitory activity, but with lower titre, was also found to be elevated in sera of some MRL/lpr mice, an animal model of SLE. Functional characterisation of the serum factors shows that: (1) the inhibitory activity cannot be neutralised by exogenous IL-2; (2) the stimulatory activity is not due to the presence of serum IL-2 but synergy of the factor with IL-2; (3) the factors bind directly to CTLL cells but they do not bind to protein A; and (4) the serum factors are not dialysable but heat labile. The possible pathological implications of the serum factors, particularly for the defective T cell functions in lupus disease, are discussed.
Department of Immunology, University of Glasgow, Western Infirmary, UK.
F P
FP
Huang
D I
DI
Stott
D000818:Animals; D001685:Biological Factors / Q000097:blood*; D002455:Cell Division; D002460:Cell Line; D004195:Disease Models, Animal; D006801:Humans; D007376:Interleukin-2 / Q000097:blood*; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D013205:Staphylococcal Protein A / Q000097:blood; D013601:T-Lymphocytes / Q000166:cytology / Q000502:physiology*
D001685:Biological Factors; D007376:Interleukin-2; D013205:Staphylococcal Protein A