Absolute and percent CD4+ T-cell enumeration by flow cytometry using capillary blood.

Area of Science:

• Clinical immunology
• Flow cytometry
• HIV diagnostics

Background:

• Venipuncture for CD4+ T-cell counting is invasive and resource-intensive.
• Alternative blood collection methods are needed, especially for vulnerable populations.
• Capillary blood offers a less invasive alternative for CD4+ T-cell level measurement.

Purpose of the Study:

• To evaluate the agreement between CD4+ T-cell counts derived from capillary blood versus venous blood.
• To assess the feasibility of using capillary blood for CD4+ T-cell enumeration in HIV-infected adults and children.
• To determine the reliability of capillary blood collection in resource-limited tropical settings.

Main Methods:

• A cross-sectional study enrolled 152 HIV-positive adult and pediatric patients in Maputo City, Mozambique.
• Peripheral blood specimens were collected via both venipuncture and finger prick from each participant.
• CD4+ T-cell counts were determined using FACSCount and FACSCalibur flow cytometers.

Main Results:

• Absolute CD4+ T-cell counts from capillary blood showed close agreement with venous blood counts on both FACSCalibur (R²=0.96) and FACSCount (R²=0.97).
• Percent CD4+ T-cell counts from capillary blood also demonstrated good agreement with venous blood on the FACSCalibur (bias +0.6%).
• The study established reliable correlation between capillary and venous blood CD4+ T-cell measurements.

Conclusions:

• Capillary blood collection provides accurate CD4+ T-cell counts comparable to venous blood.
• This validates the use of capillary blood for CD4+ T-cell enumeration in diverse patient groups.
• Point-of-care testing and tiered laboratory networks can effectively utilize both blood types for HIV monitoring.