title: Differentiation of encephalitogenic T cells confers resistance to an inhibitory anti-CD4 monoclonal antibody.
abstract: The anti-CD4 mAb W3/25 inhibits experimental autoimmune encephalomyelitis (EAE) in Lewis rats by blocking Th cell responses to encephalitogenic determinants of myelin basic protein (MBP). However, it has yet to be resolved how W3/25 modulates CD4 to inhibit EAE-associated T cell responses. This study revealed that W3/25 profoundly inhibited MBP-stimulated proliferation by sensitized lymph node cells but only partially inhibited the respective response of uncloned and cloned lines of MBP-specific T cells. That is, low concentrations of W3/25 blocked 30 to 60% of MBP-stimulated proliferation, but 100-fold higher concentrations did not result in additional inhibition. W3/25 also inhibited MBP-induced acquisition of EAE transfer activity, but only in cultures of freshly isolated lymph node cells and not in cultures of continuously propagated T cells. Studies focusing on the GP2.E5 T cell line revealed that the lack of sensitivity to W3/25 in encephalitogenic and proliferative assays was nevertheless associated with an effective blockage of MBP-stimulated IL-2 production. Importantly, W3/25 specifically inhibited antigenic but not mitogenic stimulation of IL-2 production. Reverse transcriptase/polymerase chain reaction analyses revealed that MBP-activated GP2.E5 T cells produced mRNA for both IL-2 and IL-4, and that W3/25 selectively inhibited accumulation of IL-2 as compared to IL-4 mRNA. Thus, GP2.E5 T cells apparently express a IL-4-dependent pathway that confers resistance to the inhibitory activity of W3/25. Studies focusing on two CD4+ T cell hybridomas revealed that W3/25 profoundly inhibited MBP-stimulated IL-2 production but did not affect the alternative response of MBP-induced growth inhibition. Several other hybrids also mediated MBP-stimulated IL-2 production but did not express CD4 and were not affected by W3/25. These results indicate that: 1) interactions of W3/25 with CD4 do not necessarily block class II MHC-restricted recognition of MBP; and 2) expression of CD4 is not necessary for Ag recognition by several clonotypes of MBP-reactive T cells. Rather, the results of this study are consistent with the concept that W3/25 inhibits transduction of costimulatory signals that are required specifically for initiation of IL-2 production. These findings may have important implications for understanding the therapeutic potential of anti-CD4 mAb in autoimmune disease.
authors.affiliation: Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, NC 27858-4354.
authors.forename: M D
authors.initials: MD
authors.lastname: Mannie
authors.forename: J
authors.initials: J
authors.lastname: Morrison-Plummer
authors.forename: T J
authors.initials: TJ
authors.lastname: McConnell
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D001483:Base Sequence; D015704:CD4 Antigens; D002454:Cell Differentiation; D002999:Clone Cells / Q000276:immunology / Q000473:pathology; D018076:DNA, Complementary / Q000235:genetics; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D007376:Interleukin-2 / Q000096:biosynthesis / Q000235:genetics; D015847:Interleukin-4 / Q000096:biosynthesis / Q000235:genetics; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D004676:Myelin Basic Protein / Q000276:immunology; D051381:Rats; D011917:Rats, Inbred Lew; D013601:T-Lymphocytes / Q000276:immunology* / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D018076:DNA, Complementary; D007376:Interleukin-2; D004676:Myelin Basic Protein; D015847:Interleukin-4