Centroblast

In immunology, a centroblast generally refers to an activated B cell that is enlarged (12–18 micrometer) and is rapidly proliferating in the germinal center of a lymphoid follicle.

Immunoblasts are distinguished from centroblasts by being B cell-derived lymphoid cells that have moderate-to-abundant basophilic cytoplasm and a prominent, centrally located, trapezoid-shaped single nucleolus which often has fine strands of chromatin attached to the nuclear membrane (‘spider legs’).

[5] Centroblasts do not express immunoglobulins and are unable to respond to the follicular dendritic cell antigens present in the secondary lymphoid follicles.

CD27 is an important marker for germinal center formation in the lymphoid follicle and is produced by centroblasts interacting with CD28+ helper T cells.

[2] After proliferation, centroblasts migrate to the light zone of the germinal center and eventually give rise to centrocytes.

Histopathology of a centroblast in a follicular lymphoma , H&E stain. They are relatively large cells containing vesicular nuclei with one to three basophilic nucleoli apposing the nuclear membrane.
Model of centroblast development
Histologic comparison of cell types in a germinal center , H&E stain:
- Centrocytes are small to medium size with angulated, elongated, cleaved, or twisted nuclei.
- Centroblasts are larger cells containing vesicular nuclei with one to three basophilic nucleoli apposing the nuclear membrane.
- Follicular dendritic cells have round nuclei, centrally located nucleoli, bland and dispersed chromatin, and flattening of adjacent nuclear membrane.