Abstract
Activating and inhibitory killer immunoglobulin-like receptors (KIR) and their ligands HLA-Bw4 (loci A and B) were studied by way of establishing whether they can contribute to protection against HIV-1 infection in highly exposed and persistently seronegative (HESN) patients. Twenty-three HIV-1 serodiscordant heterosexual couples, 100 HIV-1(+) patients and 200 healthy individuals were included in this retrospective case-control study. HLA typing was performed by means of PCR followed by sequence-specific oligonucleotide probe reverse hybridization. KIR3DL1 and KIR3DS1 were studied by PCR sequence-specific primers. The frequency of KIR3DS1(3DS1/3DL1)-Bw4 combination was significantly higher in HESN patients versus the discordant couples (P = 0·0003) and HIV-1(+) patients (P = 0·0001). Conversely, the KIR3DL1/KIR3DL1 homozygosity was significantly decreased in HESN patients versus the discordant couples (P = 0·00003), and HIV-1(+) patients (P = 0·00066). The frequency of HLA-A*32 and HLA-B*44 was higher in HESN versus their discordant couples (P = 0·009; P = 0·049), and HIV-1(+) patients (P = 0·00002; P = 0·0001). This had greater significance in combination with KIR3DS1 (3DS1/3DL1). KIR3DS1(3DS1/3DL1) could have a greater effect on protection against HIV-1 infection in HESN patients when bound to a specific HLA allele, in this case HLA-A*32 and HLA-B*44, both Bw4 alleles. The differences probably arise both in the HLA alleles and in the subtypes of KIR receptors depending on the ethnic group studied.