HLA-G and B-cell chronic lymphocytic leukemia: Clinical determinants that correlated with higher IgG titers and neutralizing activity included early Rai stage disease, low serum β2-microglobulin (≤2.4 mg/L) levels, lack of prior CLL therapy, vaccination ≥ 12 months following anti-CD20 therapy, and no requirement for IVIg therapy.