CD8+ T-lymphocyte percentage

Method

CD8+ T lymphocytes expressed as a percentage of total lymphocytes in peripheral blood by flow cytometry. Gating strategy and antibody panel recorded on the edge.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

Confused with the CD4/CD8 ratio, which is derived from this value and is reported alongside it. If CD4 and CD8 percentages rise proportionally the ratio does not move at all, so a null ratio together with two positive subset effects is consistent rather than contradictory — a graph that treats them as three independent findings will read one panel as three. Also confused with the CD3+ percentage, which includes this subset within it, and with the absolute CD8 count, which has a different denominator. Direction of benefit is context-dependent: a rising CD8 percentage is favourable where it reflects immune reconstitution but unfavourable where it reflects chronic activation, so the sign must be asserted on the edge.