DurgicalDurgical
EN
Open the app

Immunology · Lymphoid organs

Spleen: white pulp, red pulp, asplenia !

  • Organ

The spleen filters the blood: its red pulp removes old red cells and its white pulp starts immune responses against blood-borne germs.

Updated 2026-11-01

See it in 3D: Spleen

What it is

The spleen is the largest secondary lymphoid organ, in the left upper abdomen under the lower ribs. Its red pulp filters blood, removing aged red cells and antibody-coated bacteria, while its white pulp holds T and B cells that respond to antigens in the blood. Without a spleen, people are at lifelong risk of fast, severe infection by encapsulated bacteria.

Structure

  • Capsule with trabeculae; soft, dark red, fragile tissue.
  • Splenic artery branches into central arterioles wrapped in white pulp.
  • Blood reaches the red pulp and must squeeze through slits in the sinusoid walls, which old, stiff red cells cannot pass.

Function

  • Removes aged red cells and recycles their iron.
  • Clears bacteria and parasites coated with antibody or complement.
  • Makes antibody against polysaccharide capsules (IgM, marginal zone B cells).
  • Stores platelets and monocytes; can make blood cells again if the marrow fails.

Clinical notes

  • Splenic injury: most often injured abdominal organ in blunt trauma; left upper quadrant pain and shock.
  • Splenomegaly: infectious mononucleosis (risk of rupture with contact sports), malaria, portal hypertension, leukemias and lymphomas.
  • Sickle cell disease: repeated infarcts destroy the spleen in childhood, so encapsulated infections are a major cause of death.
  • People without a spleen are offered pneumococcal, meningococcal and Haemophilus influenzae vaccines; fever in an asplenic person is an emergency.

In the lab

  • Blood smear after splenectomy or in functional asplenia: Howell-Jolly bodies (nuclear remnants in red cells).
  • Platelets and white cells may rise after splenectomy.
  • Ultrasound and CT show size and trauma.

Test yourself

Think of the answer, then tap the question to see it.

Which cells form the periarteriolar lymphoid sheath of the white pulp?

T cells, around the central arteriole.

Which three bacteria are most dangerous after splenectomy?

The encapsulated bacteria Streptococcus pneumoniae, Haemophilus influenzae type b and Neisseria meningitidis.

What finding in the blood smear suggests absent or nonfunctional spleen?

Howell-Jolly bodies: small nuclear remnants inside red cells.

Why do patients with sickle cell disease behave as asplenic?

Repeated sickling and infarcts destroy the spleen during childhood (autosplenectomy).

Add to my cards (4)

See it in 3D

The structures of Durgical's 3D anatomy where it is found.

Microorganisms

← All of immunology

Educational content on the immune system; not a treatment or individual vaccination guide and no substitute for a health professional's advice. No doses are given.

Sources: 21.1 Anatomy of the Lymphatic and Immune Systems (OpenStax, Rice University (Anatomy and Physiology 2e), 2022); Spleen removal (MedlinePlus, U.S. National Library of Medicine, 2024); Macrophages (British Society for Immunology, 2024).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.