CELLULAR lMMUNOLOGY 143325%260 (1992) MHC-Unrestricted Recognition of Bacteria-Infected Target Cells by Human CD8+ Cytotoxic T Lymphocytes’ ELISABETH HERMANN, WERNER-J. MAYET. KARL-HERMANN MEYER ZUM BUSCHENFELDE, AND BERNHARD FLEISCHER’ Received Nowrnher l-7, 1 WI; uccepted Mu!, 10. IYYZ A CD8’ r&‘TCR+ T cell clone (A35) was isolated from the synovial fluid of a patient with postenterlc reactive arthritis caused by Yer,Pinia emerocolitica. This clone efficiently killed autol- ogous and allogeneic target cells that had been preincubated with live but not with heat-killed bacteria. There was no restriction by polymorphic parts of HLA-A, -5. or -C molecules and a HLA class II-deficient mutant cell line was lysed as efficiently as its normal counterpart. whereas infected HLA class I-deficient cells (Daudi cells) were not. The clone showed crossreaction between Yevcinro enlerocoliticu. E.sc,herichiu co/~. P.ve~rdoomonas uerngrnosa. and SIrc~~fo~x~r.c p~qgenes, but did not lyse target cells preincubated with S~~p/7~k~~c.~~~s cJ[~iderfnidr.s. MAb to CD2. CD3. and CD8 efficiently blocked A35. whereas the addition of mAb to HLA class II or to HLA class I did not. This clone apparently represents a novel effector mechanism against bacteria-infected or -modified cells that could be involved in the immunopathology of reactive arthritis. t. 1992 Academx Preys. Inc. INTRODUCTION Destruction of target cells is an important effector mechanism of cellular immune reactions toward different allogeneic or altered autologous cells and tissues. Among cytolytic T lymphocytes (CTL),j several distinct cell types have been defined ( 1). Clas- sical, MHC-restricted CDS+ CTL expressing an cv/3TCR generally recognize their spe- cific antigen as peptide in association with polymorphic parts of MHC class I molecules (2). Certain CDS+ a@TCR+ lymphocytes can also mediate, via their TCR-CD3 com- plex, “promiscuous” cytotoxicity against various tumor cells without MHC restriction (3). Recent findings suggest that in addition to a@TCR-bearing T cells, also y8TCR’ T lymphocytes can exert cytotoxic activity toward NK-sensitive as well as NK-insen- sitive (4, 5) and bacteria-pulsed (6) target cells. In particular, the Vy9-V62 subset of yaTCR+ lymphocytes displays a MHC-unrestricted cytolytic response to a heat-shock ’ This work was supported by the Kurt Eberhard Bode-Stiftung im Stifterverband ftir die Deutsche Wis- senschaft and by the Deutsche Forschungsgemeinschaft (SFB 3 I I). ’ To whom correspondence should be addressed. ’ Abbreviations used: CTL. cytotoxic T lymphocytes: B-LCL. EBV-transformed B cell line: SF. synovial fluid: Em. T cell-depleted PBMC. 253 000%8749/92 $5.00 Copyright 21 1992 by Academic Press. Inc. All rights of reproductmn in an\ form reserved.