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Differential phosphorylation--cause for defective internalization of aggregated IgG by chronic myeloid leukemic

H Desai1, S Zingde, S Advani

  • 1Cancer Research Institute, Bombay, India.

Leukemia Research
|January 1, 1992
PubMed

Insights

Chronic myeloid leukemia (CML) granulocytes show altered protein phosphorylation compared to normal cells. These differences in protein phosphorylation may explain the impaired IgG internalization in CML patients.

Area of Science:

  • Hematology
  • Cellular Biology
  • Biochemistry

Background:

  • Granulocytes from chronic myeloid leukemia (CML) patients exhibit defective internalized aggregated immunoglobulin G (IgG).
  • This defect may stem from compromised transmembrane signaling pathways.

Purpose of the Study:

  • To investigate potential alterations in protein phosphorylation in CML granulocytes compared to normal granulocytes.
  • To correlate observed phosphorylation changes with the functional defect in IgG internalization.

Main Methods:

  • Peripheral blood granulocytes from normal individuals and CML patients were isolated.
  • Cells were labeled with 32P-sodium orthophosphate and stimulated with aggregated IgG.
  • Phosphoproteins were analyzed using 2D-SDS-PAGE and autoradiography.

Main Results:

  • Five distinct phosphoproteins (Pp1-Pp5) were identified and characterized.
  • Basal phosphorylation of Pp1 and Pp3 differed between normal and CML granulocytes.
  • Stimulation with aggregated IgG induced reversed phosphorylation patterns of Pp1 and Pp3 in CML cells compared to normal cells.

Conclusions:

  • Significant differences in protein phosphorylation exist between normal and CML granulocytes.
  • Altered phosphorylation of specific proteins likely contributes to the defective IgG internalization observed in CML.

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