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Mitogen-induced B-cell differentiation in Xenopus laevis.
Differentiation; Research in Biological Diversity
|January 1, 1984
Summary
Pokeweed mitogen (PWM) stimulates Xenopus laevis spleen cells to proliferate and differentiate into immunoglobulin-producing plasmablasts. This study details the in vitro immune response, identifying IgM as the primary immunoglobulin produced.
Area of Science:
- Immunology
- Amphibian Biology
- Cell Biology
Background:
- The South African clawed toad (Xenopus laevis) serves as a model organism for immunological studies.
- Understanding B lymphocyte activation and differentiation is crucial for comparative immunology.
Purpose of the Study:
- To investigate the effects of pokeweed mitogen (PWM) on Xenopus laevis spleen cells in vitro.
- To characterize the proliferation and immunoglobulin production of stimulated lymphocytes.
Main Methods:
- Cell culture of Xenopus laevis spleen cells with PWM.
- 3H-thymidine uptake assay for proliferation measurement.
- Light and electron microscopy for cell morphology.
- Direct immunofluorescence for immunoglobulin detection.
- Biosynthetic labeling and SDS-PAGE for Ig analysis.
Main Results:
- PWM induced significant proliferation of spleen cells, peaking at 6-8 days.
- Stimulated cells differentiated into plasmablasts, with 25% containing cytoplasmic IgM.
- Xenopus lymphoblasts synthesized and secreted Ig polypeptide chains, forming monomers (H2L2) and hexamers.
- Two distinct Ig heavy chains (74 and 81 kDa) were identified, with secreted forms showing higher molecular weights.
Conclusions:
- PWM effectively induces in vitro proliferation and polyclonal differentiation of Xenopus splenic B lymphocytes into plasmablasts.
- The study confirms the synthesis and secretion of IgM in Xenopus lymphocytes stimulated by PWM.
- The findings provide insights into amphibian B cell activation and immunoglobulin production.