SAMD14 and neurabin-I as target antigen of recombinant PCNSL-derived BCRs. (A) ELISA of SAMD14 reactivity of PCNSL-derived recombinant BCRs. The columns represent adsorbence at OD 490 nm. (B) Western blots of PCNSL tissue lysates using SAMD14-specific recombinant BCR. Lane 1: PCNSL tissue from patient #3 with a BCR not reacting with SAMD14. Lane 2: PCNSL tissue from patient #6 with SAMD14 reactive BCR. Two proteins, one at 150 kDa (above) and at 45 kDa (bottom) of PCNSL, are targeted by the recombinant PCNSL-derived BCR, with both antigens from patient #6 having a higher molecular weight compared to the antigens from patient #3. (C) Identification of neurabin-I as the second antigen. Western blot of PNCSL tissue from patient #3. Lane 1: the SAMD14-specific recombinant PCNSL-derived BCR targets proteins at 145 kDa and 45 kDa; lane 2: stripped western blot for reprobing with a commercial antibody directed against the N terminus of neurabin-I, identified the 145 kDa band as neurabin-I. (D) Second isoform of SAMD14/neurabin-I in patients with SAMD14/neurabin-I-reactive lymphoma BCR. Western blots of PNCSL tissues from patients with SAMD-14/neurabin-I-specific lymphoma cell BCRs (lanes 2, 3, 4, and 5) showed a higher molecular weight than from patients with BCR specificities other than SAMD-14/neurabin-I (lanes 1, 6, and 7), whereas bands for progranulin were not different. (E) ELISA for neurabin-I reactivity of individual PCNSL-derived recombinant BCRs. The columns represent adsorbence at OD 490 nm, consistent with reactivity of the respective recombinant BCRs against neurabin-I.