CTNPT 004: Effects of HLA allele frequencies on HIV disease progression

About The Study

This study investigated the association between HLA variations and CD4 decline in Manitoba.

About The Disease

When HIV is acquired it infects the immune cells and causes a decline in a specific type of immune cell called CD4+ T-cells. Variation in the human leucocyte antigen (HLA) gene can influence the rate of CD4 decline. These genes are responsible for cellular molecules that help the immune system distinguish between the body’s own proteins and invading viruses.

The effect of the variations in this gene have been studied in both Caucasian and African patients however very little attention has been paid to those of Aboriginal descent. This population is over-represented among those living with HIV in Canada, particularly in the prairie provinces (Saskatchewan and Manitoba).

Study Approach

Two-hundred and ninety-four HIV positive participants were recruited and analyzed for their variation in HLA. Fifty-six recruited participants had the B35 variation of HLA, the B51 variation was present in 58 participants, and 10 individuals had both. One-hundred and eighty other participants were included as a control group (neither B35 nor B51).

The study measured the CD4 count at the beginning of the study, the rate of CD4 decline, HIV viral load, and opportunistic infections, among other things. The number of participants whose CD4 cell count fell below 200 cells/mL and/or had opportunistic infections was compared between the groups.

Results

Both HLA B51 and HLA B35 were found to be associated with a progression to AIDS, reaching a CD4 T-cell count of <200 cells/mL, and/or opportunistic infections. The study also found that the HLA B35 was more prevalent in this population than in other groups of people.

Conclusions

This study identified three major findings: (1) supported the association between the B35 variation and increased disease progression, (2) the B35 variation was found to be overrepresented in the study population, and (3) for the first time the HLA B51 variation was found to be associated with a faster CD4 decline.