Immunoelectrophoretic analysis of subretinal fluid and its diagnostic significance.
(1) Immunochemical examination shows that subretinal fluid can be divided into two major categories. A 'barrier pattern' is found in the presence of an effective blood-retinal barrier, whereas a 'barrier-damage pattern' emerges when there is a progressive increase in the permeability of the choriocapillarispigment epithelium complex. (2) The immunoelectrophoretic appearance of the subretinal fluid from a recent simple detachment shows a 'barrier pattern' and consists of only low molecular-size plasma proteins, since the choriocapillaris-pigment epithelium complex allows the smaller proteins to escape into the subretinal space more readily than the larger. There is, therefore, a general relationship between the clearance of any plasma protein in the subretinal space and its molecular size.(3) It is only in long-standing detachment that the permeability of the blood-retinal barrier is sufficiently altered to allow the passage of higher-molecular-weight proteins such as IgG and IgA. Increase in permeability of the choriocapillaris-pigment epithelium complex, due possibly to structural modifications, is responsible for the 'barrier-damage' pattern of the subretinal fluid. (4) There may be variations in the degree of barrier breakdown. In those retaining a highly selective barrier, little or no high-molecular-weight proteins escape in the subretinal fluid even in cases of long-standing detachment, whereas, in those with low selectivity, the leakage of high-molecular-weight proteins parallels that of the smaller proteins. (5) The apperance of very large molecules in the subretinal fluid indicates a preceding choroidal inflammation or neoplastic invasion; and the detection of IgM is, therefore, of value in the differential diagnosis of retinal detachment.
D001798:Blood Proteins / Q000032:analysis; D002199:Capillary Permeability; D005122:Exudates and Transudates / Q000032:analysis*; D006801:Humans; D007122:Immunoelectrophoresis; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D012163:Retinal Detachment / Q000378:metabolism*; D012171:Retinal Vessels / Q000503:physiopathology; D014168:Transferrin / Q000032:analysis
D001798:Blood Proteins; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D014168:Transferrin