The CD5/CD72 Receptor System Is Coexpressed with Several Functionally Relevant Counterstructures on Human B Cells and Delivers a Critical Signaling Activity

Andrea Cerutti, Livio Trentin, Renato Zambello, Rosaria Sancetta, Antonella Milani, Cristina Tassinari, Fausto Adami, Carlo Agostini, Gianpietro Semenzato

Research output: Contribution to journalArticlepeer-review

50 Scopus citations

Abstract

The CD5 molecule is expressed on T cells and, at a lower density, on a minor B cell subset (CD5+ B cells). The pan-B Ag CD72 was recently identified as the CD5 counterstructure, and several data suggest the involvement of this ligand pair in T-B cell cognate interaction. However, the functional role of CD5 and CD72 molecules within the B cell compartment is still unknown. In this work we studied umbilical cord blood CD5+ B cells (B-1a), adult splenic CD5- B cells (B-2), and CD5+ B cells from patients with chronic lymphocytic leukemia. Flow cytometry analysis and proliferation assays were used to determine 1) the ability of B-1a and B-2 cells to coexpress functionally relevant counterligands other than CD5 and CD72, and 2) the signaling capacity of CD5 and CD72 in terms of B cell activation and proliferation. To this purpose, freshly isolated or preactivated normal and neoplastic B cells were cultured with agonistic anti-CD5 or anti-CD72 mAbs in the presence or the absence of cytokines equipped with B cell activity. Our data demonstrate that CD5 and CD72 molecules are coexpressed with other ligand pairs usually involved in T-B cell cognate interaction on B-1a cells, but not on B-2 cells. CD5 and/or CD72 engagement delivers critical costimulatory signals in B-1a, B-2, and B cells from patients with chronic lymphocytic leukemia, but with different requirements and patterns. Besides suggesting the potential involvement of B-1a lymphocytes in B-B cell interactions during T-independent B cell responses, our results indicate that CD5 and CD72 counterstructures play a functional role in the B cell compartment.

Original languageEnglish
Pages (from-to)1854-1862
Number of pages9
JournalJournal of Immunology
Volume157
Issue number5
StatePublished - 1 Sep 1996
Externally publishedYes

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