FCRL6 distinguishes mature cytotoxic lymphocytes and is upregulated in patients with B-cell chronic lymphocytic leukemia.

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FCRL6 distinguishes mature cytotoxic lymphocytes and is upregulated in patients

with B-cell chronic lymphocytic leukemia.

DM Schreeder, J Pan, FJ Li, E Vivier, and RS

Eur J Immunol, November 1, 2008; 38(11): 3159-66.

Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL,

USA.

Fc receptor-like 6 (FCRL6), the most recently characterized member of the FCRL

family, is a cell surface glycoprotein with tyrosine-based regulatory potential.

An extensive survey of human hematopoietic tissues disclosed that FCRL6

expression by NK- and T-cell subpopulations increases as a function of

differentiation and is remarkably restricted to mature lymphocytes with

cytotoxic capability. In particular, FCRL6 distinguishes perforin-expressing

CD56(dim) NK cells, Vdelta1(+) and Vdelta2(+) gammadelta T cells, effector and

effector memory CD8(+) T cells, and rare cytotoxic CD4(+) T cells in adult

tissues. Analysis of this receptor in B-cell chronic lymphocytic leukemia (CLL)

was also performed. FCRL6 was found to mark significantly expanded populations

of cytotoxic CD8(+) T, CD4(+) T, and NK cells in patients with CLL. Despite

sequence homology with the known Fc receptors for IgG and IgE, FCRL6 did not

bind Ig. Although FCRL6 can be tyrosine-phosphorylated, its antibody-mediated

ligation was unable to influence cellular activation. Collectively, these

results demonstrate that FCRL6 is a distinct indicator of cytotoxic effector

lymphocytes that is upregulated in diseases characterized by chronic immune

stimulation.

PMID: 18991291