Depressed activation of the lectin pathway of complement in hereditary angioedema

The possibility of simultaneous measurement of the classical pathway (CP), mannan-binding lectin (MBL)--lectin pathway (LP) and alternative pathway (AP) of complement activation by the recently developed Wielisa method allowed us to investigate the in vivo significance of the C1-inhibitor (C1INH) in three complement activation pathways. Functional activity of the CP, LP and AP were measured in the sera of 68 adult patients with hereditary angioedema (HAE) and 64 healthy controls. In addition, the level of C1q, MBL, MBL-associated serine protease-2 (MASP-2), C4-, C3- and C1INH was measured by standard laboratory methods. MBL-2 genotypes were determined by polymerase chain reaction. Besides the complement alterations (low CP and C1INH activity, low C4-, C1INH concentrations), which characterize HAE, the level of MASP-2 was also lower (P = 0.0001) in patients compared with controls. Depressed LP activity was found in patients compared with controls (P = 0.0008) in homozygous carriers of the normal MBL genotype (A/A), but not in carriers of variant genotypes (A/O, O/O). Activity of CP correlated with LP in patients (Spearman's r = 0.64; P < 0.0001), but no significant correlation was found in the control group and no correlation with AP was observed. In contrast, the activity of CP and AP correlated (Spearman's r = 0.47; P < 0.0001) in healthy controls, but there was no significant correlation in the HAE patients. We conclude that the activation of LP might also occur in subjects with C1INH deficiency, which is reflected by the low MASP-2 and C4 levels.

The 8.1 ancestral MHC haplotype is strongly associatied with colorectal cancer

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Background: The immune system is believed to play an important role in sufficiently or insufficiently inhibiting the multistep process of tumour development. The so-called 8.1 ancestral haplotype (8.1AH) in the main histocompatibility complex is associated with alterations of the immune response characterized by an increase in antibodies, circulating immune complexes and TNF-a, and lack of a complement protein component (C4A). Methods: To study the possible association of the 8.1AH with colorectal cancer the DNA samples of 183 hungarian patients (average age 67.99 ys; 63–74 ys) with colorectal cancer and 129 healthy hungarian controls (average age 66.5 ys; 60–73.5 ys) were genotyped for member alleles of the 8.1 AH: AGER -429C, HSP70–2 -1267G (HSP70–2G), TNF- a -308A (TNF2) and LTA+252G by SSP-PCR and PCR-RFLP. Simultaneous carriage of the four member alleles was considered carriage of the 8.1AH. Results: We found the frequency of the 8.1AH to be significantly higher in patients with colorectal cancer than in healthy controls (19.1% vs. 7%, P=0.002). After adjustment to age and gender individuals carrying the 8.1AH had a 2.81 (1.23–6.22, P=0.011) fold risk to develop colorectal cancer compared with non-carriers of the haplotype. None of the member alleles alone showed association with colorectal cancer (PAGER-429C=0.486; PHSP70–2G=0.898; PTNF2=0.140; PLTA=0.376.) Conclusions: The 8.1AH by the genetically encoded alterations of the immune response may affect the development of colorectal cancer. The frequency of the 8.1AH is 5–10% in Hungary/Central Europe but, for instance, approx. 20–25% in the populations with Celtic origin. Our novel observation might contribute to cancer research and therapy when more information is available on which key components of the altered immune response encoded by the 8.1AH are not effective enough against tumor development.

No significant financial relationships to disclose.