Anti-4 hydroxy-2-nonenal immunoblot of RBC membrane of SLE and control samples: RBC membrane ghosts were prepared as mentioned earlier. Equal amounts of protein samples were electrophoresed and transferred to nitrocellulose membrane and immunoblotted with anti-HNE antibodies. Anti-rabbit horseradish peroxidase conjugate was added and the blots were developed using chemiluminecence. Lanes 1–4 corresponds to RBC membranes obtained from SLE samples while lanes 5–9 correspond to normal controls. The samples were analyzed at random on the gel and later cut out and aligned after identification as either SLE or normals. 'M' stands for molecular weight standard.