Correspondence: Prof. C Caruso, Laboratorio di Immunopatologia, Dipart- imento di Biopatologia e Metodologie Biomediche, Corso Tukory 211,

imento di Biopatologia e Metodologie Biomediche, Corso Tukory 211, 90134 Palermo, Italy. E-mail: marcoc(cid:1) unipa.it These studies have been supported by grants from MURST, Rome (ex 40%, Immunogenetics of Longevity, coordinated by Professor Calogero Caruso, to CC and DL), ex 60% to CC and DL., from Min- istery of Health Projects ‘Immunological parameters age-related’ and ‘Pharmacogenomics of Alzheimer’s Disease’, from Sicilian Government ‘Breast Cancer and Immune Response’ and by a cooperation contract between the Dipartimento di Biopatologia e Metodologie Biomediche dell’Universita` di Palermo and the Istituto Nazionale di Riposo e Cura per Anziani di Ancona (Longevity and elderly disability biological markers). Besides, the collaboration between the two groups is partly enhanced by European net- work ImAginE. Received 6 September 2001; revised 16 October 2001; accepted 16

In several cytokine genes, polymorphisms located within promoter regions, mostly single nucleotide poly- morphisms (SNP), or microsatellites, have been described which affect gene transcription, causing interindividual variations in cytokine production. These polymorphisms might confer flexibility in the immune response by allowing differential production of cytokines.11 Cytokine gene polymorphisms have been shown to be involved in the susceptibility, severity and clinical outcome of several

diseases.11–13 In particular ‘high producer’ alleles of proinflammatory cytokines have been shown to be associated with inflammatory age-related diseases14–18 and disability19, and with a decreased probability to reach extreme longevity.20

jects, and no difference was found when gender was con- sidered (Table 1).

Discussion

IL-10, a cytokine produced by macrophages, T cells and B cells, is a major immunoregulatory cytokine, usually considered to mediate potent downregulation of the inflammatory responses.21 The IL-10 production, inde- pendently by interaction with other cytokine gene pro- ducts,25 is genetically controlled by several polymorphic cht. elements in the 5 flanking region of IL-10 gene.22,26 In fact, it has been demonstrated the presence of multiple aa  SNPs in the human IL-10 5 flanking region and some of − − − these (ie 592, 819, 1082) combine with microsatellite alleles to form haplotype associated with differential IL- 10 production.22,23,26–30 Recently, three polymorphisms in the proximal region of IL-10, that might be probable tar- gets for transcription regulating factors, have been described even if conflicting results have been reported on what of these may influence, alone or in reciprocal linkage, the IL-10 transcription.31,32 However, in the proximal region of the promoter, a biallelic poly- − → morphism at 1082 (G A) has been described and the − homozygous genotype for the SNP allele 1082*G seems to be associated with higher IL-10 production respect to G/A heterozygous and A/A homozygous.23,33 The effects of this allelic promoter region difference (relative to the transcription start site) on IL-10 gene activation have been confirmed in reporter gene assays.34 On the other hand, it has been to take into account that in different cells, with different stimuli different effects may be observed.23,28,33 However, this SNP seems to be func- − tionally relevant. In fact, the 1082A carriers (ie IL-10 low producers) have been shown to be more likely to develop inflammatory diseases (or to be affected by more severe clinical patterns), such as rheumatoid arthritis and

Conversely, it can be hypothesised that anti-inflamma- tory cytokines might be involved in successful ageing and longevity. The cytokine IL-10 seems to be an appro- priate candidate from this point of view. In fact, IL-10 was recognized for its ability to inhibit activation and effector function of T cells, monocytes and macrophages, and its principal routine function appears to be to limit and ultimately terminate inflammatory responses.21 The expression of IL-10 is tightly regulated. Its levels are vari- able between individuals and almost 70% of such intra- individual variation is heritable. In fact, IL-10 production ran is controlled by several polymorphic elements in the 5 flanking region of IL-10 gene on 1q32 locus, involving alleles at two microsatellite regions and several SNPs both in distal and proximal promoter region.22

However, in the proximal promoter region, three dif- ferent inheritable haplotypes, involving three biallelic − → − → − polymorphisms at 1082 (G A), 819 (C T) and 592 → (C A) nucleotides of IL-10 promoter, have been ident- − − − ified. One containing the 1082G allele ( 1082G/ 819 − C/ 592C) seems to be associated with high IL-10 pro- − duction and two containing the 1082A allele − − − − − − ( 1082A/ 819C/ 592C and 1082A/ 819T/ 592A) seem to be associated with lower cytokine production.23 The prevalence of these polymorphisms was analysed in a large number of Italian centenarians and compared to a group of younger control subjects.

Results

− → − → − The three SNPs at 1082 (G A), 819 (C T) and 592 → (C A) under study are in strong linkage. Thus, as observed in other Caucasian populations,24 only three out of eight possible haplotypes (GCC, ACC and ATA) − − − segregate in our population. The 1082G/ 819C/ 592C haplotype was the more represented haplotype in both ± ± the controls and centenarians (0.62 0.02 vs 0.68 0.03) − − − whereas the 1082A/ 819T/ 592A was the less frequent ± ± haplotype (0.16 0.01 vs 0.13 0.02). The frequencies of − − − the 1082A/ 819C/ 592C haplotype respectively were ± ± 0.21 0.01 and 0.19 0.02. No significant differences in haplotype distribution between centenarians and controls were observed, by performing the analysis both on the whole and according to gender (data not shown).