The Sydney Blood Bank Cohort: a case-control study using a transfused HIV-1 seronegative group.

Purpose: To compare the immunological function of the Sydney Blood Bank Cohort (SBBC), a unique group of individuals who were all infected with a similar, attenuated strain of HIV-1, with a matched HIV-1 seronegative control group. To establish whether the asymptomatic state of the SBBC, in 1996, was likely to continue, and whether the SBBC were free from immunological signs of disease progression.

Methods: A prospective case-control design using a matched transfused HIV-1 seronegative control group. Immunological testing was performed and compared across the groups. These measurements included CD4+, CD8+, CD3 + subsets, total lymphocytes, beta-2-microgloublin (beta2M), and neopterin.

Results: Significant differences were observed between the SBBC and the controls, particularly CD4% (p < 0.05), CD8 counts (p < 0.01), and CD4:CD8 ratios (p < 0.001).

Conclusions: The results suggested that, as a group, the SBBC remained asymptomatic 12 to 16 years after infection with HIV-1. However, elevated CD8+ T lymphocytes, together with decreasing CD4%, suggested that some SBBC members were showing early immunologicalsigns of disease progression during late 1996, confirmed by recent (1998) follow-up studies.