Scleritis (inflammation of sclera) is a strong indication of the underlying medical problem. It can be due to fungal, viral or parasitic infection, trauma, exposure to chemicals, poisonous gases or due to post-surgical complications.
Mast cells are granulated cells typically found in connective tissue. These cells mediate immune responses to foreign particles. In particular, they release large amounts of histamine and enzymes in response to antigen recognition.
They act on H2 histamine receptors found mainly in the parietal cells of the gastric mucosa, which are part of the endogenous signaling pathway for gastric acid secretion. Normally, histamine acts on H2 to stimulate acid secretion; drugs that inhibit H2 signaling thus reduce the secretion of gastric acid.