AbstractInjection of incomplete Freund's adjuvant (IFA) into the footpads of BALB/c mice induced an acute inflammation. Draining popliteal lymph nodes showed major histocompatibility complex (MHC) class II‐restricted proliferation when challengedin vitrowith recombinantMycobacterium bovis65‐kDa heat shock protein (hsp65). αβ Tcell receptor‐positive, CD4+, hsp65‐specific T cell lines and clones were generated from these lymph nodes, and 87% of clones responded to a P galactosidase fusion protein containing residues 238–573 of human hsp60. Seventy percent of these hsp60‐responsive clones also responded to a synthetic peptide corresponding to residues 412–423 of the mouse hsp60. This peptide also induced significant responses in IFA‐primed lymph node cells but not in lymphoid cells from unimmunized mice.These results demonstrate that T cells specific for epitopes in self hsp60 are activated during inflammatory responses induced in the absence of exogenous bacterial hsp65. The findings of this study may provide a basis for understanding the often reported isolation of mycobacterial hsp65‐responsive T cells from inflammatory sites of arthritis patients, and the protective effects of preimmunization with hsp65 in experimental