Autonomous signaling of BCR from primary DLBCL cases. (A) Calcium flux assay of TKO cells transduced with BCR from six primary DLBCL with (upper row) and without (bottom row) autonomous signaling. Black triangles indicate administration of 4-OHT. Open triangles indicate anti-Ig heavy chain crosslinking. (B) Signaling strength of BCR from primary DLBCL cases and DLBCL cell lines TMD8, OCI-Ly3, and Karpas 422 (K422). All measurements of the BCR from the DLBCL cell lines during this study are shown. Symbols represent arithmetic means of two consecutive measurements. Experimental groups were compared by Wilcoxon’s signed rank test. Open symbols: BCR of IgG isotype. Solid symbols: BCR of IgM isotype. Diamond: BCR from a DLBCL originating as transformation of a follicular lymphoma. The dotted line indicates the upper limit of BCR signaling strength of non-signaling BCR. (C) BCR characteristics of primary DLBCL cases. Letters indicate one letter code of amino acids acquired by SHM relative to predicted germ-line sequences in IMGT.