MEASUREMENT OF INDUCED CYTOKINES IN AIDS CLINICAL-TRIALS USING WHOLE-BLOOD - A PRELIMINARY-REPORT

Measures of immune function have become increasingly important as endp oints in AIDS clinical trials, with respect to both modulation and rec onstitution of immunity by experimental therapies. Measurement of immu ne function in this setting requires the development of robust analyti c approaches suitable for the clinical laboratory. Experiments were pe rformed to evaluate the suitability of using cultured heparinized (''w hole'') blood for induction of tumor necrosis factor alpha (TNF-alpha) and gamma interferon (IFN-gamma), two cytokines critical in AIDS path ogenesis. TNF-alpha expression ranged from 229 to 769 pg/ml in lipopol ysaccharide (LPS)stimulated cultures and was not detected in unstimula ted cultures. IFN-gamma expression ranged from 0 to 112,000 pg/ml in p hytohemagglutinin A (PHA)-stimulated cultures and from 0 to 789 pg/ml in antigen-stimulated cultures. The mean coefficient of variation obse rved in three weekly determinations was 0.47 for TNF-alpha and ranged from 0.12 to 1.73 for IFN-gamma. These values indicate that sample siz es of 8, 24, and 29 subjects would be sufficient to detect twofold cha nges in LPS-induced TNP-alpha and in PHA- and antigen-induced IFN-gamm a, respectively, if two baseline and two treatment determinations were obtained, and if the interpatient variability of changes in true leve ls from baseline to follow-up is negligible compared to the variabilit y in the three weekly measurements. Measurement of LPS-induced TNF-alp ha and mitogen- or antigen-induced IFN-gamma can be performed simply a nd reproducibly in human immunodeficiency virus-infected persons by th e whole-blood culture method. Further studies are warranted to determi ne the effect of overnight shipping on assay reproducibility and to de termine the extent to which responses can be reliably detected in subj ects with low CD4 cell numbers.