Distinct accessory cell requirements define two types of rat T cell hybridomas specific for unique determinants in the encephalitogenic 68-86 region of myelin basic protein.
Six clonotypically unique T cell hybridomas from Lewis rats were used to study accessory cell activities required for class II MHC restricted T cell responses to the 68-86 encephalitogenic sequence of myelin basic protein (MBP). T cell hybrids which were cultured with GP68-86 68-86 sequence of guinea pig MBP (GPMBP) and naive splenocytes (SPL) were induced to produce IL-2 as measured by the CTLL indicator cell line. The hybrids were categorized into two subsets (designated THYB-1 and THYB-2), because two distinct subset-specific pathways of communication between accessory cells and T cells were involved in GPMBP-induced IL-2 production. These pathways were distinguished by the following six observations. First, when the duration of a pulse of SPL with GPMBP was lengthened from 1 to 4 h, these SPL lost their ability to induce IL-2 production by THYB-2 hybrids yet nevertheless retained full stimulatory activity for THYB-1 hybrids. Second, paraformaldehyde fixation of GPMBP-pulsed SPL abrogated an activity necessary for Ag-induced IL-2 production by THYB-2 hybrids. These fixed SPL were nevertheless able to stimulate THYB-1 hybrids, albeit to a lesser extent than viable unfixed SPL. Third, the addition of either cycloheximide, cytochalasin B, or 2-deoxyglucose to an Ag pulse of SPL with GPMBP dramatically inhibited the subsequent responses of THYB-2 hybrids yet had little or no effect upon the reactivity of THYB-1 hybrids. Fourth, thymocytes lacked necessary activities for GPMBP evoked IL-2 production by THYB-2 hybrids yet strongly promoted THYB-1 hybrid responses. Fifth, exposure of SPL to as little as 500 rad of gamma-irradiation markedly attenuated THYB-2 hybrid response to GPMBP but did not affect THYB-1 responses. Sixth, anti-GPMBP responses by THYB-2 hybrids were observed only in the presence of both radioresistant adherent SPL and a distinct population of radiosensitive nonadherent SPL. Conversely, THYB-1 hybrids exhibited full reactivity to GPMBP in the presence of adherent radioresistant SPL. Together, these observations reveal that two distinct accessory cell-T cell pathways mediate immune recognition of the 68-86 encephalitogenic region of MBP. Furthermore, these results indicate that subsets of Th cells can be defined by the accessory cell type-specific interactions that are necessary for Ag-mediated responses.
Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor 48109-0620.
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Mannie
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Paterson
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Thomas
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Nairn
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology* / Q000528:radiation effects; D002999:Clone Cells; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000276:immunology; D000939:Epitopes; D005720:Gamma Rays; D006825:Hybridomas; D008213:Lymphocyte Activation; D004676:Myelin Basic Protein / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology; D051381:Rats; D013154:Spleen / Q000166:cytology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
D000939:Epitopes; D004676:Myelin Basic Protein; D010446:Peptide Fragments