Superiority of radiobinding assay over ELISA for detection of IAAs in newly diagnosed type I diabetic children.
OBJECTIVE
Liquid- or solid-phase assays have been used for insulin autoantibody (IAA) determination, and the method of IAA measurement has not been standardized.


METHODS
IAAs were determined by radiobinding assay (RBA) and enzyme-linked immunosorbent assay (ELISA) in two large age-matched groups of nondiabetic and newly diagnosed insulin-dependent (type I) diabetic children.


RESULTS
Positivity for IAA by RBA (greater than or equal to nondiabetic mean + 3SD) was 2 of 178 (1.1%) and 55 of 173 (32%) in nondiabetic and diabetic children, respectively. Prevalence of IAA by RBA was significantly higher in the youngest age-group (63% between 0-4 yr). Positivity for IAA by ELISA was 1 of 178 (0.6%) and 8 of 169 (4.7%) in nondiabetic and diabetic children, respectively. Concordance rates between both assays were 0 of 3 (0%) in control subjects and 5 of 58 (8.6%) in diabetic children.


CONCLUSIONS
We conclude that RBA is more appropriate than ELISA for IAA detection at the onset of the disease. In addition, because available data suggest that IAAs detected by RBA only are high-affinity antibodies, it is tempting to speculate that IAAs reflect a mature immune reaction against endogenous insulin.
Levy-Marchal
C
C
Department of Diabetology, Robert Debré Hospital, Paris, France.
Bridel
M P
MP
Sodoyez-Goffaux
F
F
Koch
M
M
Tichet
J
J
Czernichow
P
P
Sodoyez
J C
JC
D000293:Adolescent; D000328:Adult; D000915:Antibody Affinity / Q000276:immunology; D001323:Autoantibodies / Q000032:analysis*; D001667:Binding, Competitive; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005069:Evaluation Studies as Topic; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D007223:Infant; D007231:Infant, Newborn; D007328:Insulin / Q000276:immunology* / Q000378:metabolism; D011853:Radiobiology; D013997:Time Factors
D001323:Autoantibodies; D007074:Immunoglobulin G; D007328:Insulin