Administration of antigen-expressing NK-cell targets results in early clearance and robust CD8⁺ T-cell responses. (A) In vivo clearance of CFSE-labeled K^b-deficient splenocytes in wild-type but not K^b-deficient hosts. Twenty-four hours after transfer, blood samples were collected and analyzed for the presence of K^b-sufficient (high CFSE) and K^b-deficient splenocytes (low CFSE). Numbers in graph represent percentage killing ± SD (n = 3). (B,C) CD8⁺ T-cell responses measured 8 days after immunization with either 10⁷ live K^b-sufficient or -deficient act-mOVA cells or with 10⁷ irradiated act-mOVA.K^b+/+ cells. Responses were quantified by IFN-γ production after stimulation with OVA peptide ex vivo (B) or the ability to kill OVA-expressing target cells in vitro (C). (D) Survival of K^b-deficient splenocytes in wild-type and anti-asialo GM1-treated recipient mice (percentage is calculated from the ratio between K^b-deficient and K^b-sufficient cells in K^b-deficient recipients for each day). (E) Frequency of antigen-specific CD8⁺ T cells in wild-type or mice receiving anti-asialo GM1 treatment before and after immunization. (F) Association curve between NK-cell presence and antigen-specific CD8⁺ T-cell responses measured after mice received different doses of anti-asialo GM1 antibody 1 day before and 1 day after vaccination with 10⁶ K^b−/− act-mOVA splenocytes.