string: The AM were isolated from the BALf and used for determination of the total cell count, differential percentage of AM and PMN, iNOS mRNA and protein, TNF-a mRNA, NF-kB and the concentration of RNI in the ex vivo incubates of the freshly isolated AM (Greenberg et al., 1994, 1995b; Kolls et al., 1995; Xie et al., 1995).