Abstract:

The use of ¹²⁵I-SPA radioimmunoassay in measuring erythocyteassociated IgG was reported in this paper. Thirty normal persons had(m±2SD 15±3agSPA/RBC, five untreated cases of autoimmune hemolutic anemia had 183±3agSPA/RBC, including one DAT negative palient who had 86agSPA/RBC. Fifteen cases of nonimmune anemia had 17±3agSPA/RBC, twelve DAT negative nonanemia casesofSLE, RA had 20±3agSPA/RBC. In comparison to DAT, this test is ten times more sensitive. The intra-run coefficient variation was 5.5%, inter-run 13%. This test is sensitive, precise and highly reproducible, but has the drawback of not being able to detect IgG₃ antibodies.