B cell Ag receptor mediates different types of signals in the protein kinase activity between immature B cell and mature B cell

Hideya Igarashi, Kazuhiko Kuwahara, Jun Nomura, Akio Matsuda, Kunimi Kikuchi, Seiji Inui, Nobuo Sakaguchi

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

Ig receptor (IgR) on the surface of B cells mediates the Ag-specific stimulatory signal for B cell proliferation and differentiation. In immature B cells, the stimulatory signal causes an inhibitory effect which is believed to be a key phenomenon in B cell tolerance or B cell anergy. Here, we studied the molecular mechanism of the inhibitory response of the IgR-mediated signal transduction that results in the programmed cell death of immature B cells. To analyze the downstream molecules of the IgR-mediated signal transduction, we prepared a mAb against a 160-kDa membrane protein (p160) that can coprecipitate the kinase molecule(s) acting on serine, threonine, and tyrosine residues. Anti-IgR stimulation induces the increase of the kinase activity coprecipitated with the p160 protein in mature B cell BAL17 and normal adult spleen B cells. This result suggests that the p160-associated kinase activity is one of the downstream events of the IgR-mediated signal transduction cascade. Interestingly, immature B cell lymphoma WEHI-231 and the neonatal spleen B cells showed the adverse reaction of the p160- associated kinase which results in the transient loss of the kinase activity. Moreover, the transient decrease of the p160-associated kinase was caused by the tyrosine phosphatase activity induced by the stimulation of IgR in WEHI- 231. The results suggest that this molecular difference in the downstream events of the IgR-mediated signal transduction between immature B cells and mature B cells already begins at the transmembrane level in the IgR-mediated signal transduction pathway.

Original languageEnglish
Pages (from-to)2381-2393
Number of pages13
JournalJournal of Immunology
Volume153
Issue number6
Publication statusPublished - 15-09-1994
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Immunology and Allergy
  • Immunology

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