Quantitation and comparison of anti-Gal-alpha-1,3-Gal antibodies in sera of healthy individuals and patients waiting for kidney transplantation.

Highly sensitized patients have poor prospects of being offered an allogeneic donor transplant, therefore, they could become primary candidates for xenogeneic organ transplantation. Hyperacute rejection is initiated by anti-Gal-(alpha)-1,3-Gal antibodies (xenoAb) and this rejection will have to be avoided if xenotransplantation is introduced into clinical practice. Hence, the aim of the study was to determine if sensitized patients against HLA antigens have higher titers of xenoAb than nonsensitized individuals. We determined immunoglobulin (Ig)M and IgG xenoAb in the serum of 100 volunteer blood donors and 98 sensitized patients and compared antibody titers from nonsensitized individuals to those with HLA specific antibodies classified into 5 panel-reactive antibody (PRA) groups: I, 0%; II, >0% and < or =10%; III, >10% and < or =50%; IV, >50% and < or =80%; and V, >80%. Analysis of the isotype specific quantification of the xenoAb revealed great interindividual variation but there were no significant differences in the range of titers of xenoAb. No significant PRA group-related variations were observed for xenoAb. In fact, there was no demonstrable correlation between levels of PRA and levels of xenoAb because the scattergram showed no statistically significant association by nonparametric statistic analysis. The results presented herein revealed that the presence of HLA specific antibody has no demonstrable relationship to the presence of higher titers of xenoAb. Thus, sensitized patients do not present a greater risk of rejection or are more difficult to treat for natural xenoreactivity than nonsensitized patients.