Waa walax kasta oo (badanaa borotiin ama sonkor ah) jirka u arko inay tahay shisheeye, taasoo kicisa nidaamka difaaca si uu uga hortago ama u burburiyo.
Maado (protein) ah taas oo laga helo xuubka kore ee unuga, kadibna kicisa difaaca jirka si loo soo saaro Difaac-jir (antibody) oo ayada lid ku ah.
Difaac-kiciye -- Antigen