title: The effect of the CD28 activation pathway on the immunosuppressive action of cyclosporine.
abstract: The effect of the CD28 activation pathway on the immunosuppressive action of CsA was assessed. Human peripheral blood lymphocytes were stimulated with anti-CD3, bryostatin (Bryo) a novel activator of protein kinase C (PKC) and anti-CD28 singly or in combination, to which graded doses of CsA were added to determine relative sensitivity. Proliferation, IL-2 production, and IL-2 receptor expression were assessed and the IC50 determined. Lymphocytes stimulated with Bryo exhibited a marginal proliferative response but expressed the IL-2 receptor despite the presence of CsA. Addition of anti-CD3 or anti-CD28 to Bryo-stimulated lymphocytes promoted a vigorous proliferative response. CsA effectively inhibited the proliferative response and IL-2 production induced with anti-CD3 and Bryo but did not inhibit the response of cells stimulated with anti-CD28 and Bryo. However, II-2 receptor expression in both sets of cultures were comparable due to the induction of IL-2 receptor by Bryo and was not inhibited by CsA. Costimulation of lymphocytes with anti-CD3 plus anti-CD28 resulted in a 2-3-fold enhancement of proliferation compared with lymphocytes stimulated with anti-CD3 alone. Addition of CsA to lymphocytes stimulated with anti-CD3 resulted in the dose-dependent suppression of the proliferative response and IL-2 production (IC50 = 10-25 nM) but less so for IL-2 receptor expression (IC50 = 100-150 nM). In comparison, the proliferative response and IL-2 production elicited by anti-CD3 + anti-CD28 was more resistant to the effects of CsA (IC50 = 100-200 nM). However, IL-2 receptor expression exhibited comparable sensitivity to CsA (IC50 = 100-200 nM) in the presence of anti-CD28. Combination drug:drug studies revealed that CsA and the protein kinase C inhibitor H-7 were additive for both anti-CD3 and anti-CD3 plus anti-CD28 response. On the other hand, the cGMP-dependent protein kinase inhibitor H-8 was synergistic with CsA in inhibiting the response of lymphocytes to anti-CD3 plus anti-CD28 but only additive for responses to anti-CD3. Taken together, these data suggest that CsA inhibits T cell activation at two distinct levels, leading to inhibition of IL-2 production and inhibition of IL-2 receptor expression. Activation of the CD28 pathway partially overcomes the inhibitory activity of CsA on IL-2 production and may be mediated by indirect activation of a cGMP-dependent protein kinase.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: Bone Marrow Transplant Unit, Johns Hopkins University, Baltimore, Maryland 21205.
authors.forename: A D
authors.initials: AD
authors.lastname: Hess
authors.forename: E C
authors.initials: EC
authors.lastname: Bright
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D054713:Bryostatins; D018106:CD28 Antigens; D017252:CD3 Complex; D003524:Cyclosporins / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000096:biosynthesis; D007546:Isoquinolines / Q000494:pharmacology; D007783:Lactones / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects*; D018942:Macrolides; D010879:Piperazines / Q000494:pharmacology; D011494:Protein Kinases / Q000502:physiology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D015375:Receptors, Interleukin-2 / Q000502:physiology*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D054713:Bryostatins; D018106:CD28 Antigens; D017252:CD3 Complex; D003524:Cyclosporins; D007376:Interleukin-2; D007546:Isoquinolines; D007783:Lactones; D018942:Macrolides; D010879:Piperazines; D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2; C046785:bryostatin 1; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C053177:N-(2-(methylamino)ethyl)-5-isoquinolinesulfonamide; D011494:Protein Kinases