Systemic Lupus Erythematosus (SLE) is a disease in which lymphoid hype
r-reactivity occurs. Whether this is primary or secondary is not alway
s clear. SLE occurs on a well defined genetic background including gen
es associated with the major histocompatibility complex (MHC) although
family studies demonstrate that other genes must be involved as well.
Other potential genes include those involved in intrinsic lymphoid hy
per-reactivity, for example by preventing programmed cell death. Such
examples exist in murine models of SLE, and in this study we provide e
vidence that one such controlling protein, bcl-2, is expressed in an i
ncreased proportion of both B and T cells in SLE patients. The increas
ed expression was not readily related to disease activity measured by
the SIS, nor by routine serological markers. This raises the possibili
ty that the increased expression of bcl-2 seen in lymphoid cells from
SLE patients may be of intrinsic genetic origin rather than being seco
ndary to the auto-reactive process. Such increased expression could be
expected to interfere with programmed cell death, to produce lymphoid
hyper-reactivity and to contribute to the induction and maintenance o
f this prototypic systemic autoimmune, disease.