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The human (PsiL+mu-) proB complex: cell surface expression and biochemical structure of a putative transducing

B Lemmers1, L Gauthier, V Guelpa-Fonlupt

  • 1Centre d'Immunologie de Marseille-Luminy, Marseille, France.

Blood
|June 11, 1999
PubMed

Insights

New monoclonal antibodies reveal the surrogate light chain (PsiL) on proB cells, identifying a novel PsiL+mu- complex involved in early B-cell differentiation signaling.

Area of Science:

  • Immunology
  • Cell Biology
  • Hematopoiesis

Background:

  • The surrogate light chain (PsiL) is crucial for pre-B cell receptor formation and early B-cell differentiation.
  • The presence of PsiL+mu- proB cells and the structure of their associated complex remain unclear in humans.

Purpose of the Study:

  • To investigate the expression and biochemical characteristics of the surrogate light chain (PsiL) in proB cells.
  • To identify novel monoclonal antibodies (MoAbs) for detecting PsiL on proB and preB cells.

Main Methods:

  • Development and characterization of new antihuman VpreB monoclonal antibodies (gamma kappa isotype).
  • Flow cytometry analysis of PsiL cell surface expression on normal bone marrow and proB leukemic cells.
  • Biochemical analysis of PsiL-associated proteins in proB cells.

Main Results:

  • Five gamma kappa MoAbs demonstrated high-affinity binding to VpreB protein, recognizing distinct epitopes.
  • MoAbs detected PsiL on both proB and preB cells, including PsiL+mu- proB cells and TEL/AML1 type proB leukemic cells.
  • Biochemical studies identified PsiL noncovalently associated with 105 and 130 kD proteins in proB cells, triggering Ca2+ flux upon complex activation.

Conclusions:

  • PsiL is expressed on both proB and preB cells, challenging previous discrepancies.
  • A novel PsiL+mu- proB cell complex exists, associated with specific proteins and potentially functioning as an early-stage receptor.
  • These findings advance understanding of B-cell differentiation and identify potential targets for leukemia research.

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