Recommended positive control: lymphoid tissues.
Staining pattern: Usually cytoplasmic, sometimes accumuolation in Golgi or perinuclear area. Rarely membranous.
Reactivity: Normal or neoplastic T-cells.
Most reliable T-cell marker. An antibody for cytoplasmic ε chain of CD3 molecules. Routinely used in diagnosis of malignant lymphoma. UCHL-1, used to be a standard antibody for T-cells, should be replaced by CD3 because of less specificity.
Normally, CD3-positive cells mainly distributed in interfollicular area. Inflammatory process may show diffuse positive pattern of CD3, therefore diffuse pattern of CD3 itself is not indicative of T-cell lymphoma. For the diagnosis of T-cell lymphoma, cellular atypia is more important, and it can be highlighted by IHC for CD3.
Figure: IHC for CD3 (normal lymphoid tissue).
Figure: T-cell lymphoma. Nuclear irregularity is clearly demonstrated by IHC for CD3.