Induction of nonspecific killer cells by delayed-type hypersensitivity against soluble protein antigens in murine peritoneal cavities.

We induced nonspecific killer cells in the local site of delayed-type hypersensitivity against keyhole limpet hemocyanin or ovalbumin. Delayed-type hypersensitivity was induced in the peritoneal cavities of mice, and peritoneal exudate cells (PEC) were collected. These PEC were found to have killer activity toward SP2 and YAC-1 cells (target cells susceptible to natural killer cells) by 4-h 51Cr-release assays. The induction of killer activity in PEC was observed in parallel with the eliciting of delayed-type hypersensitivity in the peritoneal cavity, in which the killer activity was maximum 24-48 h after the antigen challenge, but was not induced in nu/nu mice and was induced in an antigen-specific way. These killer cells did not adhere to nylon wool and had Thy1 and asialo-GM1 antigens on their surfaces. Their precursor cells were also asialo-GM1-positive. These findings indicate that the killer cells probably belong to the NK cell lineage. Results of tumor challenge experiments showed that these killer cells had an antitumor effect in vivo as well as in vitro.