Immune System

Lymph Node - Inflitration, Cellular, Histiocyte

Narrative

Comment:

Histiocytes may be increased in the lymph nodes of rats and mice. This lesion can occur spontaneously (e.g., dietary antigenic stimulation of mesenteric lymph nodes) or secondary to treatment. Increases may reflect proliferation of resident sinusoidal histiocytes or an increased influx of histiocytes via the afferent lymphatics. This lesion may be within subcapsular, paracortical, or medullary sinuses (Figure 1, arrows). If this lesion occurs in the same lymph node for a particular dose group (e.g., bronchial lymph node in an inhalation study), it may suggest a treatment-related effect. Histiocytes in affected lymph nodes may contain intracytoplasmic insoluble particulate matter, such as phagocytized test article or vehicle material (Figure 2, arrow) or pigment (hemosiderin, etc.). Histiocyte increases in lymph nodes under constant spontaneous antigenic or foreign material stimulation (e.g., mesenteric lymph nodes) must be differentiated from increases due to treatment. Previous terms for histiocytes in lymph nodes are "histiocyte hyperplasia" and "histiocyte infiltrate."

Recommendations:

Whenever present, histiocyte increases in the lymph nodes of rats and mice should be diagnosed and given a severity grade. This lesion should always be diagnosed in the context of the test article, treatment group, route of administration, and lymph node involved (compare with concurrent controls).

References:

Elmore SA. 2006. Enhanced histopathology of the lymph nodes. Toxicol Pathol 34:634-647.

Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1783683/

Elmore SA. 2006. Histopathology of the lymph nodes. Toxicol Pathol 34:425-454.

Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1892634/

Frith CH, Ward JM, Brown RH, Tyler RD, Chandra M, Stromberg PC. 1996. Proliferative lesions of the hematopoietic and lymphatic systems in rats. HL-1. In: Guides for Toxicologic Pathology. STP/ARP/AFIP, Washington, DC.

Frith CH, Ward JM, Chandra M, Losco PE. 2000. Non-proliferative lesions of the hematopoietic system in rats. In: Guides for Toxicologic Pathology.TP/ARP/AFIP, Washington, DC.

Full Text: https://www.toxpath.org/docs/SSNDC/HematopoieticNonprolifRat.pdf

National Toxicology Program. 2010. 39-Week Study (No. C20213) of Abrasive Blasting Agents (CAS No. Blastingsand) in Harlan Sprague Dawley Rats (Inhalation Studies). NTP, Research Triangle Park, NC.

Ward JM, Mann PC, Morishima H, Frith CH. 1999. Thymus, spleen, and lymph nodes. In: Pathology of the Mouse (Maronpot RR, ed). Cache River Press, Vienna, IL, 333-360.

Ward JM, Rehg JE, Morse HC III. 2012. Differentiation of rodent immune and hematopoietic system reactive lesions from neoplasia. Toxicol Pathol 40:425-434.

Abstract: https://www.ncbi.nlm.nih.gov/pubmed/22215512

All Images

Lymph node - Infiltrate, Cellular, Histiocyte in a male Harlan Sprague Dawley rat from a subchronic study. Increased numbers of histiocytes are present within the paracortical and subcapsular sinuses (arrows).

Lymph node - Infiltrate, Cellular, Histiocyte in a male Harlan Sprague Dawley rat from a subchronic study (higher magnification of Figure 1). Histiocytes contain intracytoplasmic insoluble particulate matter (arrow).

Authors and Reviewers

Authors

Kristen Hobbie, DVM, PhD
Principal Pathologist
Huntingdon Life Sciences
Peterborough, UK

Susan A. Elmore, MS, DVM, DACVP, DABT, FIATP
Staff Scientist, NTP Pathologist
NTP Pathology Group
National Toxicology Program
National Institute of Environmental Health Sciences
Research Triangle Park, NC

Holly M. Kolenda-Roberts, DVM, PhD, DACVP
Veterinary Pathologist
SNBL USA
Everett, WA

Reviewers

Jerrold M. Ward, DVM, PhD, DACVP, FIATP
Veterinary Pathologist
Global VetPathology
Montgomery Village, MD

Robert R. Maronpot, DVM, MS, MPH, DACVP, DABT, FIATP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC