**Question:** Spontaneous peritonitis in cirrhosis patients; the polymorphonuclear cells are -

A. Monocytes
B. Eosinophils
C. Basophils
D. Neutrophils

**Core Concept:** Polymorphonuclear cells, also known as granulocytes, are a type of white blood cell involved in the immune response against bacterial infections. In cirrhosis patients, spontaneous peritonitis refers to bacterial infection in the abdominal cavity without a clear source of infection.

**Why the Correct Answer is Right:** In cirrhosis patients, spontaneous peritonitis is commonly caused by Gram-negative bacteria, particularly Escherichia coli. The predominant polymorphonuclear cells in the peritoneum during an infection are neutrophils (or neutrophilic granulocytes), which are part of the innate immune response to these bacteria. Their primary function is to phagocytose (engulf and destroy) bacteria, release antimicrobial substances, and activate other immune cells.

**Why Each Wrong Option is Incorrect:**

A. Monocytes: These cells are mononuclear (single-nucleus) cells and are involved in the adaptive immune response, not the innate response against bacterial infections.
B. Eosinophils: These cells are also mononuclear cells and primarily involved in the immune response to parasitic infections, not bacterial peritonitis in cirrhosis patients.
C. Basophils: These cells are also mononuclear cells and participate in the immune response to allergens, not bacterial peritonitis in cirrhosis patients.

**Clinical Pearl:** In cases of spontaneous bacterial peritonitis in cirrhotic patients, a high neutrophil count in the ascitic fluid (serum-like fluid in the abdominal cavity) is highly suggestive of the infection. This helps differentiate between bacterial and non-bacterial causes of ascitic fluid, guiding appropriate treatment decisions and minimizing unnecessary antibiotic use.

**Correct Answer:** D. Neutrophils