CD 28 gene polymorphism and plasma concentration of soluble CD 28 in Iranian patients with visceral leishmaniasis

In visceral leishmaniasis (VL), the development of protective immunity is associated with expansion of leishmania-specific T-cell responses. Because of the essential role of CD28 in the effectiveness of T-cell activation, this study was carried out to investigate the CD28 gene polymorphism and plasma levels of soluble (s) CD28 molecule in Iranian patients with VL. Plasma concentrations of CD28 in 88 patients with VL, 132 individual with subclinical leishmaniasis, and 100 seronegative healthy controls were measured by enzyme-linked immunosorbent assay. Genotyping of CD28 gene polymorphism was performed by polymerase chain reaction based allotyping method using allele-specific primers for C or T at intron 3 position +17 in three groups. The frequency of CC genotype was significantly higher in subclinical VL patients (42.4%) than active VL group (27.3%) and healthy controls (16%) (P < 0.001). Also, the frequency of allele C among subclinical VL group (57.6%) was significantly higher than active VL (40.9%) and control groups (34%) (p = 0.003). No significant differences were observed between the plasma levels of sCD28 in three groups. Our findings suggest that the CD28 gene may have significant role in the protection of active VL in the Iranian population.