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A comparative study of the impact of HIV infection on natural
killer cell number and function in Thais and North Americans.
AIDS Research and Human Retroviruses 2000;16(11):1061-1066.
de Souza MS, Karnasuta C, Brown AE, Markowitz LE, Nitayaphan S, Garner
RP, McNeil JG, Birx DL, Cox JH.
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.