Objectives: Expression of the P1 blood type antigen is suggested to have a protective effect against post-enteropathic haemolytic uraemic syndrome (HUS). The B blood type may also protect against HUS, since terminal trisaccharide sequences similar to those of the B blood type determinants are reported to have an affinity to Vero cytotoxin that is 23% as strong as that of the P1 determinants. Thus, we studied whether ABO blood types were related to the occurrence or severity of HUS.

Methods: We obtained clinical and laboratory data of 49 HUS patients treated in 14 critical care facilities during the 1996 Escherichia coli O157:H7 outbreak in Sakai, Japan. We retrospectively studied whether ABO blood types were related to the occurrence or severity of HUS.

Results: The numbers of patients with blood types A, B, O or AB were 29, 8, 12, and 0, respectively. For each blood type, the number of patients with severe renal complications was 16, 6, 9, and 0, respectively. The distribution of blood types among the HUS patients deviated from a population-based distribution of blood types (P<0.05, Chi-squared test); i.e., the frequency of the A blood phenotype was significantly higher among our HUS patients. However, there was no significant difference in the frequency of patients with the A antigen (A and AB blood groups) among our HUS patients, whereas the frequency of B antigen expression was significantly lower (P<0.05, Chi-squared test). The risk of severe renal complications did not appear to be related to ABO blood types.

Conclusions: Our data suggest that expression of the B antigen has a protective effect against the onset of HUS, but that it does not affect the severity of the disease.