Rapid analysis of immunoglobulin isoelectric focusing patterns with cellulose nitrate sheets and immunoperoxidase staining.

Immunoglobulins which have been focused to their isoelectric points in thin-layer polyacrylamide gels can be transferred by diffusion to the surface of cellulose nitrate sheets with retention of the original focusing patterns. IgG can be detected with peroxidase-linked antiserum. Unlike polyacrylamide gel, cellulose nitrate offers no permeability barrier, and so washing times are reduced from days to minutes. Thus small quantities (less than 1 microgram) of IgG may be visualized within 24 h of isoelectric focusing. In addition after immobilization on cellulose nitrate, immunoglobulin reactivity with antigens, including those of high molecular weight, may be analysed.