The α-test: rapid cell-free CD4 enumeration using whole saliva

Area of Science:

• Immunology
• Virology
• Biochemistry

Background:

• Affordable CD4 enumeration is crucial for HIV monitoring, especially in resource-limited settings.
• Current methods are hindered by cost, technical demands, and reagent restrictions.
• Calculating CD4 counts using cell-free correlates offers a potential solution.

Purpose of the Study:

• To identify cell-free correlates for calculating CD4 counts.
• To investigate the role of alpha-1 proteinase inhibitor (α(1)PI) in CD4+ T cell regulation.
• To develop a saliva-based assay for calculating CD4 counts.

Main Methods:

• Correlated serum α(1)PI levels with CD4 counts in HIV-1 patients.
• Assessed the effect of α(1)PI administration on CD4 counts.
• Developed and validated a method to measure active α(1)PI in saliva (α(1)PI Index) by its elastase inhibitory capacity.

Main Results:

• Serum active α(1)PI levels strongly correlated with CD4 counts in HIV-1 subjects (r²=0.93).
• α(1)PI administration increased CD4 counts in both HIV-1 infected and uninfected individuals.
• The α(1)PI Index in saliva accurately reflects serum α(1)PI levels and correlates with CD4 counts.

Conclusions:

• Active α(1)PI plays a role in regulating CD4+ T cell numbers.
• The saliva-based α(1)PI Index provides a precise and affordable method for calculating CD4 counts.
• This assay has significant potential for HIV monitoring in resource-limited settings.