opsonocytophagic test

noun

op·​so·​no·​cy·​to·​pha·​gic test ˌäp-sə-ˌnō-ˌsīt-ə-ˌfā-jik- 

: a test for immunity to or infection by a pathogenic organism (as of brucellosis or whooping cough) based on the assumption that the serum of an immune or infected individual contains specific opsonins capable of facilitating phagocytosis of the organism in question