A Comparative Study of the Impact of HIV Infection on Natural Killer Cell Number and Function in Thais and North Americans

Abstract

Innate immunity may play a role in preventing HIV infection and progression to AIDS. Most studies of natural killer (NK) cell function have been conducted in populations with different HLA allele frequencies and HIV subtypes than those found in Southeast Asia. NK cell number and function, defined as CD3- cells expressing CD16+/CD56+ and the ability to lyse K562 cells, were enumerated in 42 HIV-seronegative Thais and 20 HIV-seronegative North Americans. The number and percentage of NK cells were similar for both groups, but cytotoxicity function expressed as lytic units (LU20) of NK cells was significantly greater in the Thai subjects compared with the North American subjects (p = 0.004). Comparisons were also conducted between the HIV-seronegative groups and HIV-infected subjects from both Thailand and North America. NK cell number and function were not significantly different between the Thai HIV-seronegative and -seropositive groups. However, the comparison between the North American HIV-seronegative and -seropositive subjects demonstrated profound impairment of NK cell number, percentage, and function (p < 0.001). Matching the Thai and North American HIV-infected subjects on CD4+ cell count revealed higher NK number and function in the Thai subjects (p < 0.001). The study indicates that NK function in both HIV-seronegative and -seropositive Thais is elevated relative to similar groups in North America.

Alterations of Natural Killer Cell and T-Lymphocyte Counts in Adults Infected with Human Immunodeficiency Virus through Blood and Plasma Sold in the Past in China and in Whom Infection Has Progressed Slowly over a Long Period

“…We also show that HIV infection dysregulated the NK cells with disease progression in HIV-seropositive individuals infected via past sales of blood and plasma in China. The result is consistent with findings in North American HIV-seropositive subjects (6) and another published study (17) with North American subjects, but quite different from the findings in a Thai HIV-seropositive group (6). The reasons for this difference may be related to different sample sizes, the infecting HIV subtype, or the infection time.…”

“…A previous study indicated that the NK cell percentage in Thai HIV-seropositive subjects was not different from HIV-seronegative subjects, but the NK cell percentage in North American HIV-seropositive subjects decreased compared to HIV-seronegative subjects (6). The main reason for this difference is that the disease stages of the subjects were not considered in that study; subjects studied at different stages may lead to different results.…”

“…In our study, we had a total of 225 HIV-seropositive subjects infected with HIV through past sales of blood and plasma for 8 to 11 years and who were predominantly infected with HIV subtype BЈ. Although there were 68 Thai HIV-positive subjects in that report (6) and the participants were mostly infected with HIV subtype E, the infection time was not specified.…”

HIV-1 diversity versus HLA class I polymorphism

“…26 No.1 January 2005 vary in their level of cell surface expression [62]. There are variations of KIR allele frequencies between different ethnic groups [59,60], which might correlate with reported differences in NK activity in HIV-1-infected Caucasoids and ethnic Thais [63] or the enhanced NK activity in HIV-1-exposed but uninfected Vietnamese [64]. In parallel with the MHC loci, the KIRs are also thought to be rapidly evolving in humans and primates, possibly in response to viral challenge [65].…”

Expression of monocyte markers in HIV-1 infected individuals with or without HIV associated dementia and normal controls in Bangkok Thailand

“…We have observed that the percentage of CD14CD16HLADR in normal, non-infected control Thai individuals living in Bangkok is significantly higher than similar populations in Honolulu, Hawaii. Differences in the percentage of NK cells and absolute CD4 T cell counts have been reported in Thais compared with North American controls (de Souza et al, 2000;Webster et al, 1996). It is therefore possible that the differences observed in this cohort are due to factors that are independent of HIV infection or disease status.…”