CD8 is a glycoprotein, 30-34 kDa, a MHC class I restricted receptor. CD8 binds to the nonpolymorphic region of class I molecules; it may increase avidity of cell-cell interactions. The epitope defines the CD8 suppressor-cytotoxic subtype of T-cells. CD8 positive T-cells are mainly involved in cytotoxic immunoreactions. The CD8 antigen is found on 80% of the thymocytes. In corticaL thymocytes, CD4 and CD8 are co-expressed. About 20-35% of peripheral blood lymphocytes are CD8 positive. The CD8 antigen is also found on NK cells and splenic littoral cells. 80% of the intraepithelial T-cells are CD8 positive. In refractory celiac disease, CD8 positivity is lost from the intraepithelial T-cells.
CD8 is detected in mature T-cell lymphomas, generally less often than CD4. T-cell large granular lymphocyte leukaemia and subcutaneous panniculitis-like T-cell lymphoma are most often CD8 positive (while CD4 negative).
Classification of lymphocytes, e.g., in inflammatory lesions. Classification of malignant lymphomas (see above).
Tonsil can be used as reliable control, in which both the isolated and grouped T-cells should be distinctively demonstrated.
Selected references
Mason DY, Cordell JL, Gaulard P, Tse AG, Brown MH. Immuno-histological detection of human cytotoxic/suppressor T cells using antibodies to a CD8 peptide sequence. J Clin Pathol. 1992 Dec;45(12):1084-8. Patey-Mariaud de Serre N, Cellier C, Jabri B et al: Distinction Between Coeliac Disease and Refractory Sprue: A Simple Immu-nohistochemical Method. Histopathology 37:70-77, 2000. Williamson SL, Steward M, Milton I, Parr A, Piggott NH, Krajewski AS, Angus B, Horne CH. New monoclonal antibodies to the T cell antigens CD4 and CD8. Production and characterization in forma-lin-fixed paraffin-embedded tissue. Am J Pathol. 1998 Jun;152(6):1421-6
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