PHARMACOLOGICAL ANALYSIS OF MAST-CELL MEDIATOR AND NEUROTRANSMITTER RECEPTORS COUPLED TO ADENYLATE-CYCLASE AND PHOSPHOLIPASE-C ON IMMUNOCYTOCHEMICALLY-DEFINED HUMAN CONJUNCTIVAL EPITHELIAL-CELLS

We sought to establish and immunocytochemically characterize primary c ultures of human conjunctival epithelial (HCE) cells, and to determine the types of receptors coupled to adenylate cyclase (AC) and phosphol ipase C (PLC) present on them which may be stimulated following allerg ic or inflammatory provocation of the tissue. HCE cells possessed the key epithelial cell surface cytokeratins AE1, AE3 and AE5. Signal tran sduction studies (n greater than or equal to 3), using agonists and an tagonists, revealed the presence of beta(2)-adrenergic (isoproterenol EC50 = 5.2 nM), prostaglandin E-2 (EC50 = 168 nM) and vasoactive intes tinal peptide (EC50 = 0.69 nM) receptors positively coupled to AC in H CE cells. Bradykinin (EC50 = 0.83 nM), platelet activating factor (EC5 0 = 4.5 nM), leukotriene C-4 (EC50 = 300 nM) and histamine, (EC50 = 3. 1 mu M) receptors were coupled to PLC (n = 3 for each). These data sug gest that HCE cells in vivo may represent target cells for mast cell m ediators and certain neurotransmitters which are released into the tea r-film upon allergic provocation of the conjunctiva.