The monocyte-macrophage system is affected in lysosomal storage diseases: an immunoelectron microscopic study

Studying peripheral blood mononuclear cells (PBMCs) has become an important diagnostic tool in lysosomal storage diseases. Previous studies revealed that B and subclasses of T lymphocytes participate in the storage process, whereas the role of circulating monocytes was not clear. In this study, the involvement of CD14+ monocytes in lysosomal diseases was investigated. Blood samples from six patients with different lysosomal storage disorders were studied, including one with late--infantile and three with juvenile neuronal ceroid--lipofuscinoses, and two with mucopolysaccharidosis type VI. CD14+ cells were separated immunomagnetically from PBMCs and studied by light and electron microscopy. In all investigated disorders, disease-specific lysosomal storage material could be found in monocytes. The ratio of affected to non-affected cells did not differ from previously reported data on lymphocytes and their subforms in these diseases. Our data were obtained by studying a small number of different lysosomal storage disorders. Nevertheless, they suggest that lysosomal storage in the monocyte-macrophage system might also be found in other forms of lysosomal diseases.

Leukocytes in neuronal ceroid-lipofuscinoses: function and apoptosis

The neuronal ceroid-lipofuscinoses (NCL) are a group of progressive encephalopathies with a fatal course that are mostly of autosomal recessive inheritance. The pathophysiological mechanisms causing the diseases are not known. The characteristic histomorphological feature of the NCL is an abnormal lysosomal accumulation of lipopigments in neural and extraneural cells, including peripheral blood leukocytes. We studied the function of peripheral venous blood immunocompetent cells in ten patients with NCL and in age- and sex-matched controls to determine how, if at all, the accumulation of intracytoplasmic storage material influences the functional capacity of affected tissue. Our results did not reveal any functional impairment of affected cells, but rather suggested a higher turnover rate in NCL. Apoptosis was increased, suggesting that abnormally controlled programmed cell death might play an important role in the pathogenesis of NCL.

Normal superoxide radical production in the neuronal ceroid-lipofuscinoses

The neuronal ceroid-lipofuscinoses (NCL) are a group of inherited progressive encephalopathies. Striking histomorphological feature of the NCL is the accumulation of storage material within the lysosomes in neural and extraneural cells. The basic underlying defect causing the disease is not known. Presupposing a disturbance in lipid peroxidation, some authors recommend antioxidant treatment to slow down the progression of the disease. In this study, the superoxide radical production of polymorphonuclear leukocytes as one potential source of reactive oxygen species was measured in this disorder for the first time. No significant difference in this production between affected individuals and healthy controls could be detected. Our findings cast doubt on the therapeutic benefit of antioxidant treatment.

Immunelectronmicroscopic characterization of T4 and T8 lymphocytes and natural killer cells in neuronal ceroid-lipofuscinosis

CD4+, CD8+, and CD56+ cells were isolated with the immunomagnetic separation technique from peripheral blood mononuclear cells (PBMC) of 3 patients with neuronal ceroid-lipofuscinosis: one patient each with infantile (INCL), late infantile (LINCL), and juvenile (JNCL) neuronal ceroid-lipofuscinoses, all studied by light (LM) and electron (EM) microscopy. To compare the pathology of these cells with affected cells in other types of lysosomal diseases, the separation was also performed with PBMC of 1 patient with mucolipidosis (ML) type II, 2 patients with mucopolysaccharidosis (MPS) type I, and 4 patients with MPS type III. Disease-specific lysosomal inclusions were identified in CD4+, CD8+, and CD56+ cells. Subclass-specific storage products could not be found. T4 and T8 lymphocytes showed nearly the same ratio of affected to nonaffected cells. These results suggest that lysosomal storage can be found in most of the lymphocyte subclasses in these forms of neuronal ceroid-lipofuscinoses and other lysosomal diseases.

Characterization of T-cell subclasses and NK-cells in lysosomal disorders by immuno-electron microscopy

Previous studies have shown that B and T lymphocytes are affected in lysosomal disorders. The aim of this study was to investigate the involvement of subclasses of T lymphocytes and natural killer cells in lysosomal diseases. CD4+, CD8+, and CD56+ cells were immunomagnetically separated from peripheral blood mononuclear cells in 10 patients with various lysosomal diseases--including one patient each with infantile, late infantile, and juvenile neuronal ceroid-lipfuscinoses, two patients with mucopolysaccharidosis (MPS) type I and four patients with MPS type III, and one patient with mucolipidosis type II; all lymphocytes were studied by light and electron microscopy. Respective vacuolar or non-vacuolar lysosomal inclusions were identified in CD4+, CD8+, and CD56+ cells. Subclass-specific abnormal lysosomes could not be found. Both subclasses of T lymphocytes investigated showed nearly the same ratio of affected to non-affected cells. These results were obtained by studying a small number of different lysosomal disorders. Nevertheless, they suggest that lysosomal storage in these subclasses of immunocompetent cells might also be found in other forms of lysosomal disease.