What are plasma cells & what do they do?

Answer 1

A plasma cell is a mature B lymphocyte that is specialized for antibody (immunoglobulin) production. Plasma cells are rarely found in the peripheral blood. They comprise from 0.2% to 2.8% of the bone marrow white cell count. Mature plasma cells are often oval or fan shaped, measuring 8-15 µm. The nucleus is eccentric and oval in shape. The nucleus to cytoplasm ratio is typically 2:1 to 1:1. The nucleus may be bilobed or multilobed, especially in patients with lymphoid blood dyscrasias. The perinuclear zone is very distinct, appearing white in the deeply basophilic cytoplasm. Nuclear chromatin is condensed and very patchy, appearing as dark blocks on a reddish-purple background. The cytoplasm stains deep blue to gray blue, depending on the stain and the ribosomal content of the individual cell. Plasma cells are seen in multiple myeloma, plasma cell leukemia, Waldenström's macroglobulinemia, and MGUS (monoclonal gammopathy of uncertain significance.

Plasma cells are large lymphocytes with a large cytoplasm-to-nucleus ratio and a characteristic appearance on light microscopy. They have basophilic cytoplasm and an eccentric nucleus with heterochromatin in a characteristic cartwheel arrangement. Their cytoplasm also contains a pale zone that on electron microscopy contains an extensive Golgi apparatus and centrioles. Abundant rough endoplasmic reticulum combined with a well-developed Golgi apparatus makes plasma cells well-suited for secreting immunoglobulins.

Cancer of plasma cells is termed multiple myeloma. This condition is frequently identified because malignant plasma cells continue producing an antibody, which can be detected as a paraprotein.

Common variable immunodeficiency is thought to be due to a problem in the differentiation from lymphocytes to plasma cells. The result is a low serum antibody level and risk of infections.