Comparative Study of Two Procedures for Determination of Factor VIIIR:AG Levels in Normal and Hemophilic Populations

Factor VIIIR:AG levels were determined in three populations:37 normal males (NM), 36 hemophiliacs(H) and 36 hemophiliacs with antibodies to factor VIII (HA). The procedures used were Laurell electroimmunodiffusion (EID) and radioimmunoassay (RIA) according to Hoyer. The same rabbit antibody was used for both technics. The overall correlation between the two procedures was r=0.72. When divided according to populations, the correlations were: NM r=0.90, H r=0.72, and HA r=0.60. The clinical state of the patients was then considered, i. e., the presence of bleeding or evidence of liver disease as compared to the quiescent state. In the H population using EID, the mean VIIIR:AG level in 23 quiescent patients was 1.18±0.45 u/ml and was significantly higher in 13 non-quiescent patients, 1.52±0.28 u/ml. Using RIA, VIIIR:AG levels were 1.10+0.37 u/ml and 1.24±0.25 u/ml respectively. The correlation between the two technics was relatively high (r=0.77) for the H quiescent group and low (r=0.43) for the H-non-quiescent group. In the HA group VIIIR:AG levels in 15 quiescent patients were 1.27±0.41 u/ml with EID and 0.91+0.29 u/ml with RIA. The correlation between the technics was r=0.71. These results indicate that to properly measure VIIIR:AG levels attention should be given to the clinical state of the patient at the time of sampling, and that different technics may measure different molecular forms of the factor VIII molecule.

 

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