Abstract
The effect of SLE serum on Con A induced suppressor T-cell was studied in in vitro Ig synthesis. Active SLE sera containing IgG type of Tγ specific antilymphocyte antibody (ALA) markedly inhibited the supressor T-cell activity, whereas either IgM Tγ specific ALA or any Ig classes of Tγ (-) specific ALA did not significantly affect the suppressor T-cell activity when compared with IgG Tγ specific ALA.
Other factors possibly present in SLE sera affecting the suppressor T-cell activity were also examined inin vitro Ig synthesis. Aggregated human IgG as a substitute of immune complexes inhibited Con A induced suppression of IgG synthesis in the dose dependent manner. However, their inhibitory rates were far less from those with active SLE sera containing IgG Tγ specific ALA. Corticosteroid also strongly inhibited Con A induced suppressor T-cell activity, while gel-filtration study of lupus serum revealed that the most inhibitory activity was present in IgG (7S) fraction and the removal of IgG from the sera by anti human IgG coated beads resulted in the loss of the inhibition against Con A induced suppressor T-cell activity. These results suggested that the main inhibitory factors contained in active SLE sera for Con A induced suppressor T-cell activity will be IgG type of Tγ specific ALA and other type of ALA may not contribute significantly. Circulating immune complexes and corticosteroid, if they were contained in SLE sera, seemed to play a minor role for the inhibition of suppressor T-cell activity.
