The leucocyte adhesion molecule-1 (LAM-1) is the human homologue of the murine peripheral lymph node homing receptor, MEL-14, and might play a crucial role in neutrophil localization at inflammatory sites. We have reported previously that recombinant human granulocyte colony-stimulating factor (rhG-CSF) stimulates or enhances several neutrophil functions in vivo, as well as in vitro. To further explore the possible role of G-CSF in inflammation we studied the effect of rhG-CSF on the surface expression of LAM-1 on human neutrophils, both in vitro and in vivo. The expression of LAM-1 by human neutrophils was investigated by indirect immunofluorescence using flow cytometry and monoclonal antibodies anti-Leu-8 and TQ1. A whole blood analysis was performed to minimize in vitro manipulation. Most circulating human neutrophils expressed LAM-1 on the cell surface. Brief exposure of neutrophils to rhG-CSF in vitro decreased the surface expression of LAM-1. rhG-CSF down-regulated neutrophil LAM-1 expression in a time- and dose-dependent manner. Neutrophils from healthy volunteers and from patients who were receiving rhG-CSF exhibited a decreased expression of LAM-1 after rhG-CSF administration, and the expression thereafter returned or overshot the pretreatment level after stopping rhG-CSF administration. These findings indicate that rhG-CSF down-regulates the surface expression of LAM-1 on human neutrophils in vivo, as well as in vitro, and G-CSF might participate in neutrophil-endothelial cell interaction in inflamed tissue.

Summary. Various data support the pathogenetic significance of serum IgM autoantibodies against glycolipid GM1 in patients with multifocal motor neuropathy. Although some patients with this neuropathy have an extraneural lymphoma, IgM anti-GM1 glycolipid autoantibodies have not been investigated in these cases. We found IgM anti-GM1 autoantibody in the serum of a 52-year-old man who developed multifocal motor neuropathy that was associated with an extraneural diffuse large B-cell lymphoma. An autopsy showed severe widespread demyelination without lymphoma cell infiltration in the peripheral nerves. Immunofluorescent flow cytometry and thin-layer chromatographic immunostaining demonstrated that most of the anti-GM1 antibody in the serum was monoclonal IgM of k type, which was also demonstrable in secretory form on lymphoma cells. The antibody showed affinity for the Galb1-3GalNAc terminal disaccharide of glycolipids GM1 and GD1b, which both are widespread in peripheral nerve myelin. Enzyme-linked immunosorbent assay demonstrated that this antibody was much more abundant in lymphoma cell culture supernatant than in normal lymphocyte culture supernatant. Thus, our patient's B-cell lymphoma cells produced a monoclonal IgM k autoantibody against this terminal disaccharide residue. This antibody bound to glycolipids GM1 and GD1b in peripheral motor nerve myelin, presumably initiating formation of destructive immune complexes that caused multifocal motor neuropathy.

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A 65-year-old Japanese woman was referred to our hospital because of hypereosinophilia lasting for more than 10 years, and skin ulceration, especially on the hands. Closer examination revealed the clonal proliferation of CD3-CD4+T-lymphocytes. The patient had generalized pruritus without severe end-organ involvement and high serum levels of IgE. A diagnosis of monoclonal CD3-CD4+ T-lymphocyte-associated idiopathic hypereosinophilic syndrome (HES) was made based on these findings. This case showed that this newly recognized entity of HES is not restricted to Western countries. The abnormal T-cell clone was not merely TH2 type but was clearly TH2/TH0 type. Although this disease is considered prelymphoma, this patient did not develop lymphoma during more than 13 years of follow-up. Therefore, in some patients, clonal CD3-CD4+ lymphocyte-associated HES may take a more indolent course. In this subgroup, the control of clinical manifestations seems very important. In the present case, treatment with hydroxyurea quite dramatically improved the intractable skin manifestations, although the treatment lessened only the number of peripheral eosinophils and not the number of clonal CD3-CD4+ T-lymphocytes.

Gastrointestinal tract involvement is a rare complication of plasma cell neoplasia. We present a case of non-secretory type primary plasma cell leukaemia (PCL) with multiple gastric involvement. Dual surface antigen analysis of bone marrow cells revealed that atypical plasma cells coexpressed CD38 and myeloid antigen CD13. Upper gastrointestinal endoscopy disclosed multiple submucosal masses in the body of the stomach. Endoscopic biopsy specimens showed marked infiltration of atypical plasma cells consistent with a diagnosis of gastric involvement by PCL. Since CD13 antigen is identical to aminopeptidase N, a membrane-bound glycoprotein thought to be involved in the process of tumour invasion, CD13 expression on neoplastic plasma cells may be related to the gastric involvement in this patient.