Laboratory control values for CD4 and CD8 T lymphocytes. Implications for HIV-1 diagnosis

Area of Science:

• Immunology
• Virology
• Clinical Laboratory Science

Background:

• Standard flow cytometry enables routine laboratory determination of CD3, CD4, and CD8 T lymphocyte subsets.
• Establishing normal ranges is crucial for identifying deviations, particularly those related to Human Immunodeficiency Virus type 1 (HIV-1) infection.

Purpose of the Study:

• To define the normal ranges of CD3, CD4, and CD8 T lymphocyte subsets in HIV-1-seronegative individuals.
• To investigate deviations in these subsets associated with HIV-1 infection and other conditions.

Main Methods:

• Two-colour fluorescence flow cytometry was used on whole blood samples from 676 HIV-1-seronegative individuals.
• Lymphocyte subset percentages and absolute counts were analyzed across different demographic and health groups, including controls and individuals with clotting disorders.

Main Results:

• CD4% and CD8% values demonstrated stability throughout life; CD4 counts below 25% were considered abnormal in children.
• Absolute T cell counts decreased from birth to age 10. Adult mean values were: lymphocytes 1.90±0.55, CD3 1.45±0.46, CD4 0.83±0.29, CD8 0.56±0.23 x 10(9)/l.
• HIV-1+ patients (over 60%) showed low CD4 counts (<0.4 x 10(9)/l) and inverted CD4/CD8 ratios, a combination rare in seronegative groups.

Conclusions:

• A CD4 count <0.4 x 10(9)/l and a CD4/CD8 ratio <1 are significant indicators requiring further investigation for HIV-1 or other immunodeficiencies.
• Longitudinal studies revealed that absolute CD4 counts tend to remain fixed within individuals.
• The study provides a basis for using T cell subset analysis in routine diagnostics for immunodeficiency and HIV-1 monitoring.