The recognition and classification of immunodeficiency diseases with bacteriophage phiChi 174.

A standard antigen to assess humoral responses is needed for the immunodeficiency syndromes. Bacteriophage phiChi 174 is the best available antigen. Large, standardized batches can be prepared, stored and distributed; samples for assay can be transported by mail. We have systematically studied the immune response to this antigen in over 200 persons, including 49 immunodeficiency patients. Phage provides consistent delineation of humoral responses in primary immunodeficiency diseases.