USEFUL IN DIAGNOSING T-CELL AND NATURAL KILLER CELL LYMPHOMAS. CD3 REACT WITH A SUBSET OF NATURAL KILLER CELLS THAT EXPRESS THE CYTOPLASMIC EPSILON CHAIN OF CD3. IN NORMAL TONSIL, THE T CELLS PREDOMINATE IN THE INTERFOLLICULAR REGIONS. DIAGNOSTICALLY, ANTIBODIES TO CD3 ARE USEFUL IN DEMONSTRATING T-CELL LINEAGE OF MALIGNANT LYMPHOMAS.

IMMUNE COMPLEX DETECTION BY C1Q BINDING IS USEFUL IN DIAGNOSING AND MONITORING IMMUNE COMPLEX DISEASES LIKE VASCULITIS, SLE, GLOMERULONEPHRITIS, DIFFUSE INTERSTITIAL LUNG DISEASE AND NEOPLASTIC DISEASES. TEST MAY ALSO HAVE PROGNOSTIC VALUE.

THIS TEST AIDS IN THE DIAGNOSIS OF EWING S SARCOMA. NKX2.2 IS A VALUABLE MARKER FOR EWING SARCOMA WITH A SENSITIVITY OF 93% AND SPECIFICITY OF 89%. IT HELPS IN THE DIFFERENTIAL DIAGNOSIS OF SMALL ROUND CELL TUMORS.

THE RATIO OF CD4 TO CD8 T-CELLS IS AN IMPORTANT MARKER FOR THE HEALTH OF THE IMMUNE SYSTEM. ITS PRIMARILY USED IN THE MANAGEMENT OF HIV/AIDS TO MONITOR DISEASE PROGRESSION AND THE EFFECTIVENESS OF ANTIRETROVIRAL THERAPY. A LOW CD4 COUNT IS A SIGN OF A COMPROMISED IMMUNE SYSTEM.

CD45 EXPRESSION IS VERY SPECIFIC AND QUITE SENSITIVE FOR CELLS OF HEMATOLYMPHOID LINEAGE. IT HELPS IN DISTINGUISHING LYMPHOMA / LEUKEMIA FROM OTHER NEOPLASMS. THE MAIN EXCEPTION IS CLASSICAL HODGKIN LYMPHOMA, IN WHICH CD45 EXPRESSION IS ABSENT.

CD8 IS USEFUL IN THE DIAGNOSIS AND TYPING OF T-CELL LYMPHOMAS. IT AIDS IN THE IDENTIFICATION OF CYTOTOXIC T CELLS. CD8 POSITIVITY IS ALSO SEEN IN HYPOPIGMENTED MYCOSIS FUNGOIDES. THIS TEST ALSO AIDS IN DIFFERENTIATING SPLENIC HAMARTOMA (CD8 POSITIVE) FROM HEMANGIOMA OR LITTORAL CELL ANGIOMA (CD8 NEGATIVE).

CD19 IS EXPRESSED BY NORMAL AND NEOPLASTIC B CELLS BUT IS NOT EXPRESSED BY T CELLS, MONOCYTES OR GRANULOCYTES. CD19 PROTEIN APPEARS EARLY DURING B-CELL MATURATION AND IS FOUND DURING ALL STAGES OF B-CELL MATURATION, INCLUDING PLASMA CELLS. CD19 IS USEFUL AS AN ADDITIONAL MARKER OF B CELL LINEAGE IN LEUKEMIAS AND LYMPHOMAS. EXPRESSION OF CD19 MAY BE SEEN IN SOME ACUTE MYELOID LEUKEMIAS.