Increased cAMP and cAMP-dependent protein kinase activity mediate anti-CD2 induced suppression of anti-CD3-driven interleukin-2 production and CD25 expression.
Anti-CD2 monoclonal antibody (mAb) can act synergistically with anti-CD3 to produce tolerance and diminish the anti-CD3-induced cytokine syndrome. Since interleukin(IL)-2 production and IL-2 receptor (IL-2R; CD25) expression are important determinants of CD3-driven T cell activation, the effects of anti-CD2 on anti-CD3-induced CD25 expression and IL-2 production were analyzed and related mechanistically to CD2-stimulated cAMP signaling with an in vitro model of T cell activation. The anti-CD2 mAb, 12-15, alone had no effect on splenic T cell CD25 expression and IL-2 production, while the anti-CD3 mAb, 145-2C11, caused significant increases in both CD25 expression and IL-2 production. The addition of anti-CD2 inhibited anti-CD3-induced increases in CD25 and IL-2. The inhibitory signal delivered by anti-CD2 was effective in many forms of T cell activation, since other stimuli which increased CD25, such as concanavalin A, phytohemagglutinin, and Staphylococcal enterotoxin B (SEB), could also be inhibited by anti-CD2. The inhibitory effect of anti-CD2 on CD25 could not be reversed by high doses of supplemental IL-2 added to the culture. Anti-CD2 increased cytoplasmic cAMP in a dose- and time-dependent manner. Reagents that increased cytoplasmic cAMP such as forskolin, cholera toxin, and 3'-isobutyl-1-methylxanthine could mimic the inhibitory effect of anti-CD2 on anti-CD3-driven CD25 expression. Anti-CD2 also increased the activity of cAMP-dependent protein kinase (PKA). H8, a PKA antagonist, blocked the inhibitory effect of anti-CD2 on CD25 expression, further confirming the role of PKA in CD2-induced negative signaling. The use of paired agonists to PKA demonstrated that a type I PKA was the preferential enzyme isoform stimulated by CD2 ligation. These findings show that increased cAMP and PKA activity mediate anti-CD2-induced suppression of anti-CD3-driven IL-2 production and CD25 expression, and provide mechanisms for anti-CD2-induced immunosuppression and inhibition of the cytokine syndrome associated with anti-CD3 treatment.
Lin
J
J
Department of Surgery, University of Michigan, Ann Arbor 48109-0331, USA.
Gettys
T W
TW
Qin
L
L
Chavin
K D
KD
Yang
Q
Q
Ding
Y
Y
Punch
J D
JD
Bromberg
J S
JS
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D018801:CD2 Antigens / Q000276:immunology*; D017252:CD3 Complex / Q000276:immunology* / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism* / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism* / Q000502:physiology; D004789:Enzyme Activation / Q000276:immunology; D005260:Female; D007128:Immunoglobulin Fragments / Q000494:pharmacology; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007376:Interleukin-2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D015375:Receptors, Interleukin-2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
D000911:Antibodies, Monoclonal; D018801:CD2 Antigens; D017252:CD3 Complex; D007128:Immunoglobulin Fragments; D007166:Immunosuppressive Agents; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases