A STEALTH APPROACH TO INHIBITION OF LYMPHOCYTE-ACTIVATION BY OLIGONUCLEOTIDE COMPLEMENTARY TO THE PUTATIVE G(0) G(1) SWITCH REGULATORY GENEG0S30/EGR1/NGFI-A/

A putative G(0)/G(1) switch regulatory gene GOS30/EGR1/NFGI-A shows in creased expression shortly after adding concanavalin-A (ConA) to cultu red T lymphocytes, However, it is reported that lymphocytes from mice in which the gene has been deleted proliferate normally in response to ConA. This suggests that GOS30 expression is not critical for the res ponse, Paradoxically, others report that proliferation of ConA-stimula ted rat lymphocytes is inhibited by an antisense oligonucleotide compl ementary to G0S30. Because the G0S30 sequence is highly conserved betw een species, we used a similar oligonucleotide (differing by 1 base) t o show for humans that the response to ConA is also inhibited, However , no oligonucleotide-induced changes in the concentrations of GOS30 pr otein or mRNA are detectable, This suggests that the oligonucleotide i s not acting by influencing the expression of G0S30, and may be target ing another gene, The phosphorothioated oligonucleotide was maximally inhibitory at a 50 nM concentration, which is near to the ''physiologi cal'' concentration found with CpG-containing oligonucleotides to acti vate mouse B lymphocytes, In the present work, increasing the concentr ation above 50 nM, or adding further quantities of control oligonucleo tides, decreased the inhibition, It is suggested that by using low oli gonucleotide concentrations (the ''stealth'' approach), one may avoid ''tripping'' an endogenous defense system directed against exogenous o ligonucleotides, yet still get sufficient uptake to inhibit lymphocyte activation.