Lipocortin I (Annexin I) Is Preferentially Localized on the Plasma Membrane in Keratinocytes of Psoriatic Lesional Epidermis as Shown by Immunofluorescence Microscopy

Lopocortin I (LPC-I, also called annexin I) is a 35-kD protein that binds phospholidpids and actin ina a Ca++-dependetn manner. It is also a major substrate for EGF recepto/kinase and rotein kinase C,. and a putative inhibito of phospholipase A2, which produces chemical mediators to cause inflammation. Psoriasos (PS) is an inflammatory skin disease characterized by a rapid turnover of keratinocytes and a defect in keratinization with increased activities of phospholipase C and A2, and EGF receptor. To understand the mechanism of the PS lesion formation and the function of LPC-I, its didtribution was studied in the epiedermis of PS, subacure eczema and normal skin, and in tumor, cells of seborheic keratosis and Bowen's disease. This study involved immunofluorescence and immunoblotting using affinity-purified polyclonal and monclonal antibodies specific to LPC-I and to its Ca++- bound form. In normal, nonlesional PS and subacute eczema epidermis, LPC-I was detected , mainly in the cytoplasm of the suprabasal cells, although it was on the inner aspects of the plasma membrane in some parts of the granular layer. In lesional epidermis of PS it was localized mainly on the inner aspects of the plasma membrane, but not in the cytoplasm of the whole suprabasal cells as the Ca++-bond form, indicating a preferential localization of the plasma membrane. This membrane-binding of LPC-I was also observed in seborrheic keratosis, but not in Bowen's disease. These results suggest that the binding of LPC-I to the plasma membrane occurs actually in living cells, plays a role not necessarily disease specific, in the PS lesion formation, and has some relevance to normal or abnormal differentiation of keratinocytes

Epidermolysis Bullosa Acquisita: Ultrastructural and Immunological Studies

Four patients with epidermolysis bullosa acquisita were investigated using immunofluorescence, routine electron microscopic and immunoelectron microscopic techniques. Immunofluorescence studies demonstrated linear immunoglobulin and complement deposition along the dermal-epidermal junction. These findings are similar to those seem in skin of patients with bullous acquisita from that seen in bullous pemphigoid. Indirect immunoelectron microscopic findings suggest that epidermal basal cells of affected patients may secrete the dermal substances to which the antibodies bind