This project is intended to identify the routes on which BAFF and APRIL act in order to detect possible future candidates to Belimumab treatment among patients diagnosed of SLE.

DESIGN Establish the influence of certain polymorphisms in the levels of expression of different transcripts and proteins.

Quantify the levels of B cell activating factor belonging to the TNF family (BAFF) and a proliferation-inducing ligand (APRIL) in serum and urine of patients and controls by Enzyme-Linked Immunosorbent Assay (ELISA). BAFF Determine the expression levels of different BAFF and APRIL transcripts in peripheral blood mononuclear cells from patients and controls using a digital PCR (polymerase chain reaction) system.

Compare distribution of gene polymorphisms in BAFF and APRIL in patients and controls. by sequencing the exome of the ligand and receptor genes using next generation sequencing (NGS).

Correlate the transcript and protein levels with clinical manifestations and disease activity.

The results of the quantification of anti- double-stranded deoxyribonucleic acid.(dsDNA) antibody levels tests will be recorded together with those demographics, clinical-epidemiological and response to the treatment.data.

Inclusion criteria

• Women18-60 years old
• For patients only treated with conventional drugs (without immunosuppressive or biological treatment )
• For Healthy controls: no autoimmune diseases (blood donors) diagnoses

SLE (Sistemic Lupus Disease) with and without nephritis and healthy controls

Sharing the data collected and analysed with the scientific community by publication

When study is finished

Data publication for collaborator, data base registration of results if applicable.