The non-malignant CLL repertoire, which comprised between 1.5 and 71.3% (median of 4.6%) of the total CLL repertoires, showed IgD and IgM isotype frequencies similar to healthy repertoires, with a predominant expression of IgA1/2 and IgG1/2 (mean of 37%). The gene discussed is CD40LG; the disease is B-cell chronic lymphocytic leukemia.