Immunological Testing - Other Flow Cytometry Markers


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Immunological Testing

Other Flow Cytometry Markers

Numerous additional parameters can be measured by flow cytometry but their role in patient management is not defined. CD8+ T lymphocytes are cytotoxic T cells (CTL), which play an important role in protection against viral infection. The number of circulating CD8 cells increases significantly during primary HIV infection, and remains moderately elevated until very late stages of disease. However, most studies show that the CD8 count is not a significant independent marker of disease progression.

CD4 and CD8 lymphocytes also can be characterized according to their activation state by staining for CD38, HLA DR, or CD25. As with CD8+ cells, the proportion of activated cells (either CD4+ or CD8+) tends to be higher in infected patients with HIV infection as compared to control.

The proportion of activated cells drops with initiation of effective antiretroviral therapy. Analysis of data from the Multicenter AIDS Cohort Study (MACS) have shown that the proportion of CD8+CD38+ cells is an independent prognostic marker of disease progression even after controlling for CD4 count and virus load (69). However, measurement of CD38 has not been adopted widely in clinical practice. Likewise, measurement of the proportion of memory and naïve CD4 or CD8 cells is of interest from the point of view of pathogenesis studies, but is not used clinically at this time.

4/15/01