An original perifollicular zone cell in the canine reactive lymph node: a morphological, phenotypical and
C Fournel1, J P Magnol, T Marchal
1Laboratoire d'Hématologie-Cytologie-Immunopathologie, Ecole Vétérinaire de Lyon, Marcy l'Etoile, France.
Insights
Canine perifollicular zone (PZ) cells, identified in reactive lymph nodes, are likely resting B cells involved in immune responses. These cells may represent an early stage in B-cell differentiation or a post-follicular stage.
Area of Science:
- Veterinary Pathology
- Immunology
- Canine Lymphocyte Biology
Background:
- Canine reactive lymph nodes exhibit complex cellular changes during immune responses.
- The perifollicular zone (PZ) is a distinct region within lymph nodes, but its cellular composition and function in dogs are not fully elucidated.
- Understanding lymphocyte subpopulations is crucial for diagnosing canine immune-mediated diseases and cancers.
Purpose of the Study:
- To characterize the canine perifollicular zone (PZ) cell using multiple advanced techniques.
- To determine the immunophenotype and potential B-cell differentiation stage of the PZ cell.
- To investigate the association of PZ cells with specific pathological conditions in dogs.
Main Methods:
- Cytological, histological, immunocytochemical, and electron microscopical analyses were performed on 109 canine reactive lymph nodes.
- Immunolabeling assessed CD3, cytoplasmic immunoglobulin (cIg), and Ki-67 expression.
- Cellular morphology and location within the PZ were meticulously documented.
Main Results:
- The PZ cell was consistently found with plasma cell hyperplasia in a well-defined perifollicular zone.
- Morphologically, PZ cells are medium-sized with fine chromatin, a prominent nucleolus, and scant cytoplasm, suggesting poor differentiation.
- Immunophenotyping revealed a CD3-, cIg-, Ki-67- profile, indicative of resting B cells.
Conclusions:
- Canine PZ cells are likely resting B cells, possibly representing a pre-follicular B-cell subpopulation or a post-follicular stage.
- Their frequent presence in reactive lymph nodes associated with mammary tumors, lupus erythematosus, and leishmaniasis suggests a role in canine immune responses.
- PZ cells may also be involved in abnormal B-cell maturation processes in dogs.
Abstract:
In this study of 109 canine reactive lymph nodes, the perifollicular zone (PZ) cell was characterized by cytological, histological, immunocytochemical and electron microscopical techniques. The PZ cell was always found in association with plasma cell hyperplasia. Its main cytological characteristics were medium size, fine chromatin and a large central prominent nucleolus with a small amount of pale cytoplasm. It was located in a clearly recognizable PZ surrounding the follicles; this zone was particularly well developed at the capsular pole of the lymph node. Electron microscopical findings indicated a poorly differentiated cell. Immunolabelling indicated a CD3-, cIg-, Ki-67- immunophenotype, suggesting a resting B cell. These results suggest that the PZ cell belongs either to a post-follicular stage between large immunoblasts and plasma cells or, as is more likely, to a pre-follicular lymphoid subpopulation occurring early in the B-cell differentiation scheme, as with most human marginal zone (MZ) cells. Its high frequency of occurrence in reactive lymph nodes in mammary tumour lymphadenopathies, systemic lupus erythematosus and leishmaniasis, suggests that the PZ cell has a special role in the canine immune response, or perhaps in the arrested maturation of the normal developmental process.
