Low levels of the immunoregulator Semaphorin 4D (CD100) in sera of HIV patients

Semaphorin-4D (CD100), generated by CD4/CD8 T-cells and its receptor on B cells – CD72, play a role in immune regulation. Both have soluble forms - sCD100/sCD72. sCD100 and sCD72 levels were determined by ELISA (MyBioSource, USA). 28 chronic HIV patients and 50 matched healthy volunteers participated in our study. Before treatment, CD4 T-cells counts were 267 ± 216 cells/mcl and viral load (VL) was 586,675 ± 1897,431 copies/ml. Two years following HAART, CD4 T-cells counts rose to 475 ± 264 cells/mcl and VL dropped to 2050 ± 10,539 copies/ml. CD8 T-cells counts were stable. sCD72 levels prior (4.13 ± 2.03 ng/ml) and following HAART (3.53 ± 2.01 ng/ml) were similar to control levels (4.51 ± 2.66 ng/ml). sCD100 levels before (40.47 ± 31.4 ng/ml) and following HAART (37.68 ± 29.44 ng/ml) were significantly lower compared to controls (99.67 ± 36.72 ng/ml) despite the significant increase in CD4 T-cells counts. The permanent low levels of the immunoregulator sCD100 suggest a role for CD100 in the immune dysfunction and T cells exhaustion of HIV.