Background: Psoriasis is a severe, long-lasting, immune-mediated, hyperproliferative, and inflammatory skin condition that can cause painful or itchy lesions and have a significant impact on quality of life. Psoriasis' complex and poorly understood etiopathogenesis.PlxinB2 has an impact on T-cell morphology that is mediated via CD100. Consequently, they play a function throughout an immune response.
Objectives: Asses serum level of plexin B2 in psoriatic patients& find any possible correlation between serum level of plexin B2 and Psoriasis Area and Severity Index (PASI) score.
Patients and methods: Cross sectional-case control study was carried on psoriatic patients who came to the Dermatology Outpatient Clinic of South Valley University Hospitals. The study started with 50 psoriatic patients& 50 controls healthy individuals unrelated, age, sex, BMI matched with volunteers. The Psoriasis Area and Severity Index score ( PASI ) used for evaluation of psoriasis vulgaris severity, then serum plexin-b2 level  was measured using commercial available ELISA Assay kit .
Results: Regarding patient's age, the 2 groups were matched for age (p=0.064). Likewise, the mean BMI (p = 0.614) sex distribution was comparable in all groups with (p =1.000), there was significantly higher mean of serum Plexin-B2 in cases (10.3 ± 2.3 pg/ml) compared to control (4.3 ± 0.3, p<0.001 pg/ml) (p=0.011), there was significant (<0.001) positive high correlation between s. plexin-b2 and disease severity (r=0.703),
 Conclusion: The current work confirming high serum plexin-b2 in psoriasis vulgaris in a high significant manner with the disease severity so, plexin-b2 may have role in psoriasis vulgaris pathogenesis.