What is contained in eosinophil primary granules?

The primary granules of eosinophils are unique in that they primarily contain specific proteins and granule proteins that are crucial for the immune response against parasitic infections and in allergic reactions.

Charcot-Leyden crystals are derived from the breakdown of eosinophil granules and are composed mainly of a protein called Galectin-10, which is secreted by eosinophils. The presence of Charcot-Leyden crystals is often associated with allergic conditions and can be seen in certain tissues during eosinophilic inflammation. Their formation indicates the activation and degranulation of eosinophils, suggesting they play a role in the immune response.

In contrast, substances like heparin, cytokines, and histamine are associated with different cells or functions within the immune system. Heparin is typically found in basophils and mast cells, cytokines are produced by various immune cells but are not stored in eosinophil granules, and histamine is primarily released from mast cells and to some extent from basophils. None of these are contained within the primary granules of eosinophils.

Thus, the correct answer reflects the unique composition of eosinophil granules and their involvement in