CD16 + 56-PERCENT

What is CD16 a marker for?

CD16 is a marker for natural killer (NK) cell. NK cells are cytotoxic cells. They are known for acting upon and destroying virus-infected cells, detect and control early signs of any cancer and limit cancer spread and tissue damage by killing tumor cells. As NK cells are present in placenta, they also play an important role in maintaining pregnancy. High NK cell levels in women of child bearing age group are at a greater risk of pregnancy loss.

What is CD16 and CD56?

CD16+CD56 are a marker for natural killer (NK) cells. NK cells are type of lymphocytes which develop in thymus gland and play an important role in innate immunity. They possess few properties and markers of T-cells but are not completely called as T-cells. NK cells are involved in regulating body’s response during viral infection and tumor surveillance. They act as first line of defense and primitive response as these cells can work without requiring any initial antigen presentation. NK cells secrete cytokines like interferon gamma and alpha which act upon cells of immune system (macrophages and dendritic cells) thereby enhancing body’s immune response (adaptive immunity).

What is the blood test for natural killer cells?

CD16 + 56-PERCENT test is about measuring circulating NK cells in the body and sees their levels in various congenital and acquired diseases. The blood test for NK cells is done by Flowcytometry analysis. In this, first the lymphocytes are separated from other white blood cells using CD45 gating. Then T lymphocytes expressing CD3, CD4, CD8 and B lymphocytes expressing CD19 are separated out. Subsequently absolute value and percentage of NK cells in a given sample is reported. Biological reference range for CD16+CD56 (NK-CELLS) % is 02-27% and absolute count is 27-693 Cells/uL.

What Causes Low natural killer cells?

Low NK cells are seen in HIV infection, some medications, malignancies, severe physiological or emotional stress and congenital deficiencies. Reducing levels of NK cells in HIV1 infection correlates with the disease progression. Low values or deficiency of NK cells increases the susceptibility to getting viral infection with herpes virus. NK cells influence the course of chronic viral infections like EBV, Hepatitis C virus, HTLV-1 and HIV – AIDS. Long standing infection with these viruses has a negative impact on NK cells leading to development of structurally and functionally abnormal NK cells. EBV infects non-neoplastic NK cells, cause them to proliferate and can subsequently cause extranodal lymphomas, especially in pediatric and young adult age groups. This is collectively referred to as systemic EBV infection plus T-cell or NK-cell LPDs of childhood. A unique feature of EBV associated LPDs is presence of severe inflammatory and necrotic skin reactions. HTLV-1 is implicated in adult T cell leukemia / lymphoma.

What are the indications of doing NK-cell testing?

Various indications of doing NK cell testing is as follows: a) Women with fertility problems, bad obstetric history and repeated abortions, b) Assessment of patients suspected to have primary immune deficiencies due to NK cell defects, c) Predicting prognosis and starting antibiotic treatment against opportunistic infections in patients with T cell immunodeficiency, d) Assessing patients undergoing solid-organ transplantation and to look for immune reconstitution after bone marrow or hematopoietic cell transplantation, e) Identification of chronic viral infections like Hepatitis C and HIV (human immuno-deficiency virus), f) Evaluating effects of Epstein-Barr virus (EBV) and human T-lymphotropic virus type 1 (HTLV-1) infection, g) Lymphoproliferative disorders (LPDs) expressing NK cells include chronic NK-cell lymphocytosis, aggressive NK-cell leukemia, large granular lymphocytic leukemia, blastic NK-cell lymphoma, extranodal NK/T-cell lymphoma and hepatosplenic T cell lymphoma ( mucosal or cutaneous gamma/delta lymphoma). Few of these cancers are EBV positive and h) Evaluation of NK cells in solid tumors like retinoblastoma, medulloblastoma, astrocytoma and neuroblastoma.