International CD4 Counting Multicenter Study

Roland Göhde r.goehde at
Fri Jun 11 13:27:26 EST 2004

Dear Colleagues,

I would like to inform you on a recently published international CD4  
counting multicenter study which evaluates new alternatives for  
accurate and affordable HIV monitoring:

Cassens, U. et al: "Simplified volumetric flow cytometry allows  
feasible and accurate determination of CD4 T lymphocytes  in  
immunodeficient patients worldwide", Antiviral Therapy 9:395-405 (2004)  
(ISI Impact Factor 6.57), International Medical Press 1359-6535/02 

The abstract of this study is given as follows:
The determination of CD4 cells is of crucial clinical importance for  
patients with AIDS. However, the high costs involved represent  
limitations for CD4 cell counting in developing countries. In order to  
provide an affordable technique, we introduced a simplified volumetric  
counting (SVC) technique without sample manipulations and investigated  
it in a multicentre study. Blood samples from 434 healthy donors and  
immunodeficient patients were tested in eight hospital laboratories in  
Europe, Africa and Asia. CD4 cell counts were compared using in-house  
flow cytometric methods and the SVC technique. The SVC method was  
performed on a low-cost flow cytometer (CyFlow SL, Partec, Münster,  
Germany) after 15 min antibody incubation without pre-analytic  
manipulations, such as washing or erythrocyte lysing procedures. Linear  
regression analysis demonstrated a correlation of r=0.942 (Europe),  
r=0.952 (Africa) and r=0.989 (Asia) between the SVC technique and the  
in-house methods. Bland Altman plot analysis of all patient data showed  
a mean bias between the two methods of +26 CD4 cells in favour of the  
SVC technique (measured range: 6–1905 cells/µl; median CD4 cell count:  
388/µl). Three centres used the FACS-count technique (Becton-Dickinson,  
San José, Calif., USA) as an in-house method dispensing with  
pre-analytic manipulations. The comparison of SVC and FACS-count method  
revealed a mean bias of +32 CD4 cells/µl (median CD4 cell count:  
349/µl). The accuracy of the SVC was tested on standards with known CD4  
cell counts (n=6) and was shown to be 95.2%. The low-cost device and  
the simplified no-lyse, no-wash test procedure reduces the costs per  
determination and facilitates the use of flow cytometry in developing  

Best regards

Roland Göhde
HIV/AIDS Project Coordinator

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