Osteopontin is a multifunctional protein with known roles in bone remodeling, wound healing, and normal and pathological immune responses. We showed in microarray studies that osteopontin gene expression is increased in human immunodeficiency virus type 1 (HIV-1)-infected lymphatic tissues after treatment, and we undertook mapping experiments to study osteopontin's possible functions in this context. We discovered species-specific colocalization of osteopontin with the follicular dendritic cell (FDC) network in lymphatic tissues in HIV-1 and simian immunodeficiency virus infections, and we found that changes in FDC-associated osteopontin covary with changes in lymphoid follicles during acute and late stages of infection and in response to treatment. We propose that this localization normally facilitates antibody production and plays a role in B cell abnormalities in infection and in the reconstitution of lymphoid follicles with treatment and that mapping genes identified in microarray studies is a useful experimental approach to gaining a better understanding of function in the context of a particular tissue and disease.
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Received 17 February 2005; accepted 9 May 2005; electronically published 25 August 2005. Potential conflicts of interest: none reported. Financial support: National Institutes of Health (grant R01 AI 056997); National Cancer Institute, National Institutes of Health (contract NO1-CO-124000 to J.D.L.). Reprints or correspondence: Dr. Ashley T. Haase, Dept. of Microbiology, University of Minnesota, MMC 196, 420 Delaware St. SE, Minneapolis, MN 55455 (email@example.com).