HomeDREAMLow-cost alternative for CD4 cell counts
05 - Ago - 2004

Low-cost alternative for CD4 cell counts found effective
Source : J Acquir Immune Defic Syndr 2004; 36:1006-1010
Last Updated: 2004-07-20

NEW YORK (Reuters Health) – Coulter cytosphere assay is an inexpensive alternative to flow cytometry for measuring CD4 cell counts, a multinational team of researchers from India report.

The need for a "simple reliable and cost-effective immunologic marker" for CD4 assay prompted Dr Pachamuthu Balakrishnan from YRG Care Centre for AIDS Research and Education, Chennai, India, and colleagues to evaluate a manual method commonly used for measuring blood cell counts.

CD4 lymphocyte counts of 122 HIV-positive patients in various disease stages were evaluated using the conventional flow cytometry and the low-cost cytosphere assay using a commercial Coulter manual CD4 kit. In the low-cost method, the blood sample was mixed with monocyte-blocking and CD4-cytosphere reagents and CD4 count carried out manually using a Coulter hemocytometer.

Overall, there was a close correlation of 0.97 between the CD4 counts using flow cytometry and those using the Coulter cytosphere assay, Dr. Balakrishnan and colleagues report in the August issue of Journal of Acquired immune Deficiency Syndromes.

The correlation was most accurate for CD4 counts less than 200 per microliter, with the sensitivity, specificity, positive and negative predictive values being 94.9%, 96.4%, 92.5% and 97.6% respectively. The mean difference in the CD4 cell count between the two methods was only 10 cells per microliter, the researchers note.

Coulter cytosphere assay is cost-effective, requiring only an initial investment of $500 for the microscope and $10 per test as compared to an initial cost of $40,000 and $1000 annual cost for flow cytometry, Dr. Balakrishnan’s team writes.

"The inter- and intrapersonal variability was within acceptable limits and the reproducibility is excellent," Dr. P Balakrishnan told Reuters Health.

As the only requirements are a microscope and a week’s training, the cytosphere assay can be carried out even in primary care settings, he said.

"Hence, the cytosphere assay can be used as an alternate to flow cytometry for estimation of CD4 T-lymphocyte counts, especially in resource-poor settings of developing countries," Dr. Balakrishnan and colleagues conclude.

Source : J Acquir Immune Defic Syndr 2004; 36:1006-1010


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