title: Human antibodies to phosphocholine. IgG anti-PC antibodies express restricted numbers of V and C regions.
abstract: We examined the IgG subclass composition and isoelectric focusing (IEF) spectrotype pattern of naturally occurring human IgG antibodies that bind phosphocholine (PC) and found direct evidence for restricted expression of both V and C regions among these antibodies. In most individuals, the isotype of these IgG anti-PC antibodies was primarily IgG2. However, serum from some individuals contained significant amounts of IgG1 and IgG3 anti-PC antibodies. We also found that in individual sera, anti-PC antibodies are pauciclonal, as demonstrated by restricted spectrotypic patterns of the anti-PC antibodies. The IEF pattern of these antibodies were for the most part unique for each individual. In some sera, certain anti-PC antibodies with isoelectric points of basic pH bound PC conjugated to bovine serum albumin (PC-BSA) but did not bind pneumococcal C-carbohydrate bearing PC determinants. In two individuals, we found that the spectrotypes that bound only PC-BSA were of the IgG1 subclass. Taken together, these findings demonstrate that within individual sera, human antibodies to PC are quite restricted in both V and C region expression, and furthermore, these V and C regions of human Ig may not randomly associate.
mesh_terms: D001323:Autoantibodies / Q000276:immunology* / Q000302:isolation & purification; D002794:Choline / Q000031:analogs & derivatives*; D006801:Humans; D007127:Immunoglobulin Constant Regions / Q000032:analysis; D007074:Immunoglobulin G / Q000145:classification / Q000276:immunology* / Q000302:isolation & purification; D007135:Immunoglobulin Variable Region / Q000032:analysis; D007525:Isoelectric Focusing; D010767:Phosphorylcholine / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D007127:Immunoglobulin Constant Regions; D007074:Immunoglobulin G; D007135:Immunoglobulin Variable Region; D010767:Phosphorylcholine; D002794:Choline