Q: I have read that sjogrens and lupus are closely related like sisters or cousins
but my doc says they are only related by the fact that they are both autoImmune.
My question is how closely related are they???
A: Sjogrens(Sjs) and Lupus (SLE) can occur together, in which case one will be designated Secondary Sjs, or each may present alone. They are both immune dysregulation disorders causing autoimmunity (both autoantibodies, termed humoral immunity, and lymphocyte dysregulation, termed cellular immunity). It appears that in SLE, the antigen that is triggering the autoantibodies is in the nucleosome (within nucleus of cells), and in Sjs the antigen is ribonucleic acid (ribosomes with cells in cytoplasm-outside the nucleus). It still is not known what is triggering these normal host antigens to cause autoantibody formation. Viral triggers or pieces of viruses (retroelements) may play a role, as well as dysfunctions that occur in the host/self immune regulatory pathways.
Clinically, Sjs patients do not have dsDNA antibodies (a hallmark for SLE). But SSA and SSB antibodies can occur in either condition.
The main clinical difference to watch for is a serious condition of the kidney (nephritis), which occurs in SLE much more commonly than Sjs. The earliest sign may be protein in the urine. Sjs patients can get nephritis, it's true but this is rare. A condition called renal tubular acidosis can occur in Sjs (but rare), and would be unusual in SLE.