Effects of analytical method and lyophilized sera on measurements of apolipoproteins A-I and B: an international survey.
In 1987 a collaborative study was initiated with 140 laboratories worldwide to evaluate the effects of analytical method and lyophilization on the measurement of different concentrations of apolipoproteins (apo) A-I and B in four lyophilized serum pool samples. This survey confirmed that the lyophilized apo Reference Material of the International Union of Immunological Societies (IUIS) is useful for apo A-I assays as an international serum-based reference material, because among-method variation is negligible. The apo A-I concentration value of 1.24 g/L is now assigned to the IUIS Reference Material (CDC 1883) by a Centers for Disease Control RIA in-house reference method. Use of lyophilized serum preparation as a reference material for some modes of apo B measurement is questionable because of lyophilization and matrix effects. Both radial immunodiffusion and liquid immunoprecipitin methods demonstrated bias in measured apo B concentrations, compared with overall method-weighted means values on the IUIS Reference Material. Because of the uncertainty associated with LDL primary standard, protein analysis, and concentration differences among analytical methods, assigning a single apo B concentration value to the IUIS Reference Material appears inadvisable at present.
Smith
S J
SJ
Division of Environmental Health Laboratory Sciences, Centers for Disease Control, Atlanta, GA 30333.
Henderson
L O
LO
Hannon
W H
WH
Cooper
G R
GR
D000704:Analysis of Variance; D016632:Apolipoprotein A-I; D001054:Apolipoproteins A / Q000097:blood* / Q000592:standards; D001055:Apolipoproteins B / Q000097:blood* / Q000592:standards; D002624:Chemistry, Clinical / Q000592:standards*; D005612:Freeze Drying; D006801:Humans; D007106:Immune Sera / Q000592:standards; D007118:Immunoassay / Q000592:standards; D012015:Reference Standards; D013048:Specimen Handling
D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D001055:Apolipoproteins B; D007106:Immune Sera