Provided are a composition, food and drink that exert, through oral ingestion of a lactic acid bacterium, a culture product thereof, a processed product thereof or a composition comprising the same, an effect of enhancing an immune response to an antigen, said antigen being administered via another route such as subcutaneous injection. A composition for oral ingestion for enhancing the proliferation of cytotoxic T lymphocytes (CTL) specific to an antigen and the production of an antibody specific to the antigen, said composition comprising a lactic acid bacterium strain Lactococcus lactis subsp. lactis capable of enhancing the proliferation of CTL and the production of the antibody, a culture product thereof or a processed product thereof and being to be used together with the antigen in the form of a vaccine.
