A type of column chromatography which is used to separate antigens from a mixture. The lab technique makes use of an immunoadsorbent -- a solid, stationary matrix within the column to which antibodies are attached. As the mixture flows through the column, the antibodies bind to the antigens; the antigens thus stay within the column while the rest of the mixture continues through to the end. The antigens are then flushed out of the column and collected separately.