Pediatric Rheumatology Online Journal → July 2003 → Childhood Lupus→ Immunology and Immunogenetics → Abstract #88

CHARACTERIZATION OF PLASMA CELL PRECURSORS IN THE BLOOD OF CHILDREN WITH SLE

E. Arce,¹ L. Bennett,¹ C. Chalouni,² G. Jego,² S. Scholl,¹ J. Banchereau,^1,2 V. Pascual.^1,2

¹Pediatric Rheumatology, UT Soutwestern Medical Center, Dallas, TX; ²Baylor Institute for Immunology Research, Dallas, TX

We have recently described the expansion of a plasma cell precursor (PCP) population in the blood of pediatric SLE patients. The presence of these cells in the blood is not a unique feature of SLE, as they can be found in healthy donors as well as in patients with a variety of autoimmune diseases. In healthy and disease situations, blood PCP display phenotypic characteristics of memory and plasma cells. As memory B cells, they express sIg, HLA-DR, CD86 and CD95. As plasma cells, they express high levels of CD38, lack CD20 and CD22 expression and contain intracytoplasmic Ig. We have found that blood PCP are oligoclonal, express mainly switched isotypes, especially IgA, and spontaneously secrete low levels of Ig on overnight cultures. We have looked at their expressed VH gene repertoire and found no significant differences in controls versus SLE patients. While the number of blood PCP is persistently elevated in SLE patients, this number fluctuates in healthy individuals most likely as the result of exposure to environmental triggers. Our data suggest that plasma cell differentiation in SLE is reminiscent of normal secondary immune responses, and that that the quantity, and not the quality, of these responses underlie the disease status.