Galactose-deficient IgA1 has been proposed as an important effector molecule in IgA nephropathy (IgAN). We previously showed that the galactose-deficient IgA1-specific monoclonal antibody KM55 can detect circulating galactose-deficient IgA1 in patients with IgAN, enabling us to study the molecular roles of galactose-deficient IgA1. Herein, we further examined the pathophysiological significance of galactose-deficient IgA1 in glomerular deposits of patients with IgAN by immunohistochemistry using KM55. Immunostaining of galactose-deficient IgA1 with KM55 was performed in paraffin-embedded sections of renal biopsy specimens from 48 patients with IgAN and 49 patients with other renal diseases such as lupus nephritis, HCV-related nephropathy, IgA vasculitis with nephritis (IgA-VN), and membranous nephropathy. Glomerular galactose-deficient IgA1 was specifically detected in IgAN and IgA-VN but not in the other renal diseases. Galactose-deficient IgA1 was localized predominantly in the mesangial region as IgA deposition. However, galactose-deficient IgA1 was not detected in patients with lupus nephritis accompanied by glomerular IgA deposition. Thus, our study strongly suggests that IgAN and IgA-VN have a shared feature regarding galactose-deficient IgA1-oriented pathogenesis.

To evaluate the safety, immune responses, and antitumor responses after the administration of α-galactosylceramide (αGalCer) KRN7000-pulsed PBMC cultured with IL-2 and GM-CSF (IL-2/GM-CSF-cultured PBMCs), a phase I-II study in patients with non-small cell lung cancer was conducted. Patients with advanced non-small cell lung cancer or recurrent lung cancer refractory to the standard therapy were eligible. αGalCer-pulsed IL-2/GM-CSF-cultured PBMCs (1 × 109/m2) were i.v. administered four times. Immune responses were monitored weekly. Twenty-three patients were enrolled in this study and 17 cases (73.9%) completed. No severe adverse event related to the treatment was observed. After the injection of αGalCer-pulsed IL-2/GM-CSF-cultured PBMCs, an increased number of IFN-γ-producing cells in the peripheral blood were detected in 10 patients (58.8%). Five cases remained as stable disease, and the remaining 12 cases were evaluated as progressive disease. The estimated median survival time (MST) of the 17 cases was 18.6 mo (range, 3.8 to 36.3 mo). Ten patients who displayed increased IFN-γ-producing cells (≥2-fold) showed prolonged MST (31.9 mo; range, 14.5 to 36.3 mo) as compared with poor-responder patients (n = 7) MST (9.7 mo; range, 3.8 to 25.0 mo) (log-rank test, p = 0.0015). The administration of αGalCer-pulsed IL-2/GM-CSF-cultured PBMCs was well tolerated and was accompanied by the successful induction of NKT cell-dependent immune responses. The increased IFN-γ-producing cells that result from αGalCer stimulation in PBMCs were significantly associated with prolonged MST. These results are encouraging and warrant further evaluation for survival benefit of this immunotherapy.

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The administration of α-GalCer-pulsed APCs successfully induced the dramatic infiltration and activation of iNKT cells in the tumor microenvironment.