Apoptosis induced by crosslinking of CD4 on activated human B cells

Giovanna Cutrona, Nicolò Leanza, Massimo Ulivi, M. Bernardetta Majolini, Giuseppe Taborelli, Simona Zupo, Cosima T. Baldari, Silvio Roncella, Manlio Ferrarini

Research output: Contribution to journalArticlepeer-review

Abstract

Using immunofluorescence, RT-PCR, and Western blotting, we have demonstrated the ability of human B cells to express CD4. In each of the 10 lymphoblastoid cell lines (LCL) tested there was variable, but definite, proportion of CD4-positive B cells. Expression of CD4 was related to the cell cycle; CD4 was expressed in the G1 phase and continued at later phases of the cell cycle. CD4 was in part internalized and degraded by the LCL B cells. Surface CD4 was associated to lck and its crosslinking resulted in tyrosine phosphorylation. Additional experiments conducted on freshly prepared tonsillar B cells demonstrated that CD4 was expressed by large activated B cells, but not by small resting B cells. However, not all the activated tonsillar B cells had surface CD4 since germinal center cells were CD4- negative. Crosslinking of CD4 on LCL or on tonsillar activated B cells resulted in apoptosis in vitro, a finding that indicates the capacity of CD4 to deliver functional signals to B cells and to play a regulatory function in their physiology. Exposure of CD4 expressing B cells to gp120 under conditions that resulted in CD4 crosslinking also caused apoptosis suggesting some implications for the pathophysiology of AIDS.

Original languageEnglish
Pages (from-to)80-89
Number of pages10
JournalCellular Immunology
Volume193
Issue number1
DOIs
Publication statusPublished - Apr 10 1999

ASJC Scopus subject areas

  • Cell Biology
  • Immunology

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