The present study investigated the expressed number of CR1 on erythrocytes (E) in
relationship of the CR1 density genotype from 46 patients with systemic lupus erythematosus
(SLE) and 47 healthy volunteers. The CR1 genotype was determined by a method based
on polymerase chain reaction (PCR) amplification of the genomic DNA fragment of 1.8
kb separated by HindIII endonuclease digestion and agarose gel electrophoresis. Our
data supported the earlier results that the number of binding sites/E for monoclonal
anti-CR1 decreased among SLE patients compared with normal individuals having the
same alleles for the CR1/E density. At the same time the novelty of our recent results
was that the decreased expression of CR1 on E correlated significantly with kidney
involvement in patients homozygous for the CR1/E high density allele (HH). These data
suggest that the deficiency of the detectable number of CR1 on erythrocytes is acquired
in this SLE population.
