Current understanding of systemic lupus erythematosus.

Following recognition of its milder forms, SLE has emerged as a major inflammatory rheumatic disease. The etiology of SLE is unknown although genetic, hormonal, and infective factors are implicated. There is a weak familial tendency and SLE frequency is raised in individuals with complement deficiencies. In a recent U.K. family study, 80% of SLE patients had a null allele at the C4 locus, compared with 20% of normals. Despite findings from animal studies there is no direct evidence for infective etiology in human SLE. Lymphocytotoxic antibodies have been found in up to 50% of household contacts of SLE patients, and viral antigens (particularly C-type) have been demonstrated in tissues from SLE patients. Hormonal factors play an important part in the disease. The female to male ratio is 9:1, rising to 30:1 in the main childbearing years and there is a tendency towards exacerbation of SLE in the puerperium. Preliminary evidence suggests that males with lupus may have abnormal estrogen metabolism. The parts played by hormonal factors on the immunological aberrations in SLE are uncertain. Abnormalities of the idiotype network in SLE have been confirmed in a number of studies. Patients with active SLE frequently experience impairment of suppressor T-cell function, which may contribute to the proliferation of circulating humoral antibodies. Siblings of SLE patients have asymptomatic abnormalities of suppressor T-cell function and, interestingly, most abnormalities were found in female siblings. Treatment in SLE has become more conservative; most patients in remission do not need treatment.(ABSTRACT TRUNCATED AT 250 WORDS)