BCR and systemic lupus erythematosus: The p65 NF-kB subunit activation (i.e. its nuclear translocation) was evaluated in nuclear extracts obtained from HD B lymphocytes (n = 6) or from SLE patients (n = 5) whole B cell population (i.e. CD20+LAIR1+ and CD20+LAIR1−) before or after cross-linking of BCR alone or with LAIR1 engagement (fig.