Autoimmune Lymphoproliferative Syndrome
Utility: Diagnostic screen for autoimmune lymphoproliferative syndrome.
Specimen: 4 - 10 mL peripheral blood in sodium heparin (green top).
CPT codes: 86359, 86360, 86355, 86357, 88184, 88185 x 11, 88188.
Clinical indication/general description
Autoimmune lymphoproliferative syndrome (ALPS), also known as Canale-Smith syndrome, is caused by a defect in apoptosis (programmed cell death) of lymphocytes via the Fas pathway leading to the abnormal accumulation of lymphocytes. Patients with ALPS present clinically with lymphadenopathy, hepatosplenomegaly and autoimmunity (autoimmune cytopenias and other autoimmune disorders) and have an increased, long-term risk to develop lymphomas.
Normally, less than 1 percent of T cells that express the T cell receptor alpha and beta chains (TCRaB+) do not express either the CD4 or the CD8 co-receptors. These T cells are termed double negative T-cells (DNT). In ALPS, the number of TCRaB+DNT cells is increased. Additionally, the TCRaB+DNT in ALPS express an isoform of CD45 that usually is expressed only on B cells, the B220 antigen. An increased number of B220+, TCRaB+DNT cells are found in all characterized forms of ALPS.