The role of Interleukin -18 / Interleukin -18 BindingProtein in Rheumatoid Arithritis patients

Rheumatoid arthritis (RA) is a chronic inflammatory polyarithritic disease associated with remission and exacerbation with different immunological features.Rheumatoid factor(RF) screening test was used quantitatively and qualitatively using an enzyme immunoassay (EIA), RF-isotypes (RF-IgG, RF-IgM, RF-IgA) , Interleukin-18 (IL-18) and Interleukin – 18 binding protein (IL-18BP) were detected quantitatively usingenzyme linked immunosorbent assay(ELISA). Results indicated a 51% positivity in RF among RA patients and a prevalence of the RF-isotype (RF-IgM) with the highest level at (41.6±16.3 U/ml) (p 0.05) among other RF-isotypes at a percentage of 85.5% , results also indicatedan elevated serum level of IL-18 and IL- 18BP(225±24.8 pg/ml), ( 5.2 ± 2.1 ng/ml ) respectively compared to healthy control (HC)group (65±8.4 pg/ml )(p 0.01) , ( 2.9 ± 1.3 ng/ml ) (p 0.05) respectively, and ratio of IL-18/IL-18BP serum levels in RA patients were significantly higher than in HC group (p 0.05) which increased the importance of IL-18BP in therapeutic strategy. In conclusion RF-IgM may be an important complimentary detection method for RA among the other isotypes ,IL-18 with its IL-18BP may play an important role in RA which need to be further investigated.