Comparison of the optical emission-line properties of 55 low-redshift (z less than 0.5) QSOs with their 2 keV X-ray luminosities has revealed two previously unseen correlations. The asymmetry of the H-beta profile and the ratio of the emission in the Fe II complex at 4550 A to that in H-beta are strongly correlated with X-ray luminosity, while correlations between X-ray luminosity and other line parameters, including the Fe II equivalent width, are probable. These correlations do not seem to be attributable to orientation effects and appear to be followed by both radio-loud and radio-quiet objects. Consistent with photoionization models, these results suggest that there exists an X-ray-absorbing region in the broad-line clouds in which Fe II emission arises from collisional excitation. A contribution to the H-beta emission from collisional excitation in the same region may also explain the H-beta asymmetry/X-ray luminosity correlation, as well as low Ly-alpha/H-beta intensity ratios.