Anti-HLA and anti-HPA Ab levels are not associated with refractoriness among LCA⁻recipients. Peak class I (A) and class II (B) HLA Ab NBG ratios and normalized maximum absorbance values for HPA Abs (C) were compared between CR⁻ and CR⁺ LCA⁻ recipients, and mean values were compared using a 1-tailed unpaired t-test. The dashed line marks the cutoff used to distinguish positive and negative results. Error bars display mean and standard error.