45 Study on CD4 cell responses in HIV infected subjects in Nepal BR Tiwari, 1 P Ghimire 2 and S Malla 3 1 Nepal Red Cross Society, Central Blood Transfusion Service; 2 Central Department of Microbiology, Tribhuvan University and 3 National Public Health Laboratory, Kathmandu, Nepal Corresponding author: Mr. Bishnu Raj Tiwari, NRCS, Central Blood Transfusion Service, Kathmandu, Nepal, e-mail: bishnu_117@yahoo.com ABSTRACT HIV infection is characterized by gradual deterioration of immune function mainly the CD4 cells. This study was conducted with the objectives to evaluate the kinetics of CD4 cell depletion and duration of HIV infection and the role of ART in improving CD4 cell levels specifically in Nepalese HIV patients. During April 2005 to March 2006, all together 220 blood samples collected from 110 HIV patients visiting National Public Health Laboratory (NPHL), Kathmandu, were analyzed for CD4 cell count using standard protocol. CD4 cell count before and after starting of anti-retro viral therapy showed significant association (P<0.05). The results of this study clearly indicated that antiretroviral therapy has been playing a role in maintenance CD4 cell counts in HIV infected patients. Keywords: HIV infection, CD4 cell count, ART, Nepal. INTRODUCTION HIV infection is characterized by a gradual deterioration of immune function. Most notably, crucial immune cells called CD4 cells are disabled and killed during the typical course of infection. 1 HIV is persistent and ultimately progressive in the vast majority of untreated hosts, there is increasing evidence that HIV have specific cellular immune responses playing a major role in determining the tempo of viral replication and thus the clinical outcome of infection. 2 In humans, evidence supporting a protective effect of cellular immune responses in HIV infection is less direct. Long-term nonprogressive infection has been associated with both strong virus-specific CTL and with robust gag p24-specific CD4 cell proliferative responses. 3 Indeed, some studies have reported a direct inverse correlation between viral load and HIV-specific T-cell responses in untreated HIV-infected subjects. 4 CD4 cell count is used to determine how well the immune system is working in people who have been diagnosed with HIV. The pattern of CD4 cell counts over time is more important than any single CD4 cell value because the values can change from day to day. The CD4 cell pattern over time shows the effect of the virus on the immune system. CD4 cell counts generally decrease as HIV progresses untreated HIV-infected subjects. 4 This study was designed to understand the CD4 cell depletion kinetics and role of anti-retroviral therapy (ART) in maintaining CD4 cell count based at National Public Health Laboratory (NPHL) where HIV/AIDS patients are referred for CD4 cell evaluation before starting and during ART. MATERIALS AND METHODS This was a cross-sectional descriptive study conducted during April 2005 to March 2006, based at NPHL with the voluntary involvement of HIV seropositive (HIV +) Nepalese males and females. The study population comprised of 110 HIV visiting NPHL, Kathmandu, during the study period. At least two blood samples from each case were collected (taking all due precautions) at the interval of six months. Information on antiretroviral therapy and other treatments were collected by filling a questionnaire from the participants. An informed consent taken from each of the participant included. Three milliliters of blood samples from each subject were collected in K 3 EDTA. The collected samples were subjected for CD4 cell count within an hour of collection following standard aseptic procedures. CD4 cell count was done using dedicated Flow Cytometry Absolute Cell Count System at NPHL using standard protocol 5 employing standard quality control system. The results of the test were recorded in excel-sheet and analyzed using standard statistical tools as required. All subjects were further categorized based on the 1993 revised classification system for HIV infection by CD4 cell count categories (<200, 200-499 and >500 cells/ mm 3 ). 6 The subjects having the CD4 cell count less than 200/mm 3 were selected for the course of ART. RESULTS A total of 220 blood samples from 110 HIV+ (62 males and 48 females) were analyzed. Out of total 110 HIV+, 52.0% were under ART and the remaining 48.0% were not (Table-1). The status of CD4 cell count before and after 6 months of receiving ART and subjects not under ART are shown in Fig. 1. The mean CD4 cell count in Original Article Nepal Med Coll J 2008; 10(1): 45-47