antigen-presenting cell

n.
  1. A cell, originating in the bone marrow and subsequently found as a dendritic cell in various locations, that facilitates the immune response by holding antigens on its surface and presenting them to lymphocytes.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.