Figure 3.

Cytokine principal component plots showing clusters at baseline (in nonsmokers). The cytokine concentration distributions are visualized according to the evaluated compartments, NLF, NELF, sputum, and serum. Cytokine concentration values were transformed using data reduction approaches (i.e., PCA) to illustrate the overall trends in cytokine groupings in 2-D. The illustrated principal components show the resulting reduced values, which captured the majority of variance in data across samples. Cytokine clusters are shown as shaded shapes within these PCA plots. NELF, nasal epithelial lining fluid; NLF, nasal lavage fluid; PCA, principal component analysis; 2-D, two dimensional.