It has been reported previously that environmental antigens such as intestinal microflora play an important role in an age-associated increase in number of T-cell receptor gamma/delta-bearing T cells. To extend the scope of this finding, this study examined the influences of local inflammation on the accumulation and/or proliferation of gamma/delta T cells in athymic nude mice injected subcutaneously with complete Freund's adjuvants (CFA). The inguinal lymph nodes (ILN) in nude mice injected with CFA in their hind footpads 7 days previously contained an increased number of CD3+CD4-CD8- cells. Increased levels of proliferative responses against syngeneic stimulator cells were noted in the LN cells of CFA-injected nude mice in association with increases in expression of gamma- and delta-chain gene messages. Furthermore, the LN cells showed an early proliferative response to purified protein derivative (PPD) from Mycobacterium bovis. These results suggest that local inflammation by CFA may induce functional gamma/delta T cells in nude mice, which may proliferate rapidly at the inflamed sites and represent a first line of defence in such animals against the invasion of various pathogens.