active immunity see acquired i. artificial immunity acquired (active or passive) immunity produced by deliberate exposure to an antigen, as in vaccination. cell-mediated immunity (CMI), cellular immunity acquired immunity in which the role of T lymphocytes is predominant.genetic immunity innate i.mmunity resulting from the development within the body of antibodies or sensitized T lymphocytes that neutralize or destroy the infective agent. This may result from the immune response to an invading organism or from inoculation with a vaccine containing a foreign antigen.