ABSTRACT
Complement 3, complement 4, properdin; and properdin C3b complex and Complement receptors [CR] [CR1 + CR11 and FC GAMA receptors] were studied in 61 patients. [8 - 20 yr.] 26 males, 35females, from AI-Azhar University Hospitals, 14 were SLE, 47 were RA. The results obtained were compared with 24 normal control. A significant decrease in C3, C4 in SLE and RA. A non significant difference in properdin in SLE and RA. A significant increase in P-C3b complex in SLE and RA. Asignificant decrease in CR1 receptor expression on neutrophils and lymphocytes of SLE, while no change with RA. Ahigh significant increase in CR11 expression on blood lymphocytes, in SLE but a non-significant difference with RA The results of FC GAMA receptor II expression on blood cells showed non significant difference in SLE and RA. Complement CR III expression on Blood cells showed a non significant diference in RA. The results of [FC- GAMA RIII] expression on monocytes showed significant increase and on neutrophils decreased and no difference on lymphocytes of SLE patients. From the study: C3, C4, and properdin-C3b complex can be used as an indicator of activity of the disease in SLE and RA inspit of no change of properdin Level. Also in cases in which C3 level is normal [30%] of SLE. Cases. C RI expression was found decrease on neutrophils of SLE while no change on expression in RA. It is possible to say that to diagnose SLE. C3, C4, P-C3b complex and CR1 expression should be measured to confirm the diagnosis of SLE