Thus, it has been shown that the phosphopeptide P140 issued from the spliceosomal U1-70K small nuclear ribonucleoprotein (snRNP) protein is recognized by lupus CD4+ T cells, transiently abolishes T cell reactivity to other spliceosomal peptides in P140-treated MRL/lpr mice and ameliorates their clinical features. This evidence concerns the gene CD4 and systemic lupus erythematosus.