LABORATORY INDICATORS FOR MONITORING HIV DISEASE

Immunological monitoring of disease progression following HIV infectio n and seroconversion illness, latency and AIDS, not only helps in the basic investigation of the natural history of the viral infection in m an, but also can assist in prognosis and treatment of AIDS-defining il lnesses. However, outside clinical trials, these tests should be selec ted and used in clinical practice only if they are validated as releva nt and effective. The absolute CD4+ T-helper lymphocyte count, measure d by flow cytometry, has emerged as the best available investigation, but needs care in sampling due to diurnal and circadian rhythms, effec ts of age, pregnancy, therapy, intercurrent infections and technique. Sampling should provide a baseline and trends - monthly intervals init ially, then quarterly in uncomplicated cases. Thresholds may be given for counts (e.g. 200/mu l) below which prophylaxis against pneumocysti s pneumonia should be administered, and repeating persistently low cou nts (e.g. below 50/mu/l) is seldom helpful in practice. Serum levels o f beta-2 microglobulin, neopterin and immunoglobulins rarely add infor mation. Physicians and laboratories should have testing guidelines bas ed on clinical audit of best practice, based in turn on scientific und erstanding of the immunological processes involved.