- 作者：Anne Halpin ; Deanna Manna ; Luis Hidalgo ; Patricia Campbell
- 刊名：Human Immunology
- 出版年：2012
- 出版时间：October, 2012
- 年：2012
- 卷：73
- 期：supp_S
- 页码：64
- 全文大小：30 K
Aim
To investigate the use of an antigen density correction factor (ADCF) for class I and II single antigen beads (SAB).Methods
Class I and II SAB (One Lambda Inc) were labelled using mouse monoclonal antibodies (Ab) specific for Class I (W6/32) and Class II (WR18) HLA antigens (Ag). The WR18 Ab reacts with HLA DR, DQ and DP. A PE labelled anti-mouse Ab was used to detect the monoclonal Ab (Jackson Immunoresearch). Weak and strong titres of the W6/32, WR18 and PE conjugate Ab were evaluated. Consistently lowest ranked beads (LRB) were assigned a ratio of 1.0 for each SAB kit. A ratio to the LRB was determined by averaging the LRB value for high and low titres of Ab. Using the LRB, the ADCF was determined and applied to patient antibody results (n = 20, 6 class I SAB, 14 class II SAB) to investigate whether or not results appeared to be more standardized. Beads with the same antigen typing were compared.
Results
Ag density of the Class I and II beads is variable. High titre W6/32 MFI values ranged from 10,000 to 19,500 vs. lower titre MFI values from 3400 to 8600. High titre WR18 MFI valures ranged from 9742 to 20,824 vs lower titre values from 2158-12,705. The ADCF varied from 1-2.39 (W6/32) and 1-2.78 (WR18). There is greater variability at with weaker Ab staining as compared to high titre of Ab. Adjusted patient MFI values still show variability in staining between same antigen beads although some beads are now more positive than others.
Conclusions
There is a range of Ag density on the class I and II SAB. The variability in staining appears to be greater with weaker dilutions of Ab. Adjusting for this variability in the Ag density may not standardize the patient sera reactivity thus we are unsure of the utility of this adjustment ratio. Comparison of the ADCF patient MFI results to flow crossmatch results may reveal if the adjusted MFI results are more clinically useful. It is not difficult to measure the antigen density on SAB and we will use this information to assess new lot numbers of SAB.