Increased frequency of HLA-DR3 and complotype SC01 in Mexican mestizo patients with amoebic abscess of the liver.

Our preliminary study (31 patients) of HLA frequencies and amoebic abscess of the liver (AAL) in Mexican mestizos was extended to include 110 patients with this condition. The previously found increase in HLA-B16 was not confirmed, but the frequency of HLA-DR3 was again found significantly increased in patients with AAL when compared to the normal, ethnically matched control population, both in its isolated (35.5% vs 12.7%) and in the HLA-A2, DR3 haplotypic version (20.9% vs 4.5%). Moreover, seven of the 17 HLA specificities that were found to be individually different at P (yet not at PC) level in patients with AAL when compared to the control population, were actually HLA-DR3 containing haplotypes. HLA-DR3 may thus encode a risk factor(s) for AAL, at least in the Mexican mestizo population. Furthermore a significant increase in the complotype SC01 and its haplotypic version SC01, DR4 were identified in 45 non selected patients with AAL when compared to normal controls (31.1% vs 6.7% and 17.8% vs 0% respectively). Even though a relationship between allelic forms of complement components and their function has not been fully established, this complotype could represent a risk factor as well, since complement appears to play a role in host defence against amoebic invasion. Finally, no extended haplotype preference was found in these AAL patients.