Magnetic sorting of leukocytes

Magnetic filtration of surface-labeled cells has been applied to the fractionation of leukocytes in a model system, using a colloidal magnetite reagent to label mouse spleen cells. This reagent was completely free from problems of aggregation or settling. Since the individual submicron particles were invisible under the microscope, cells were not visibly altered by labeling. Viability also was unaffected by either labeling or magnetic filtration. Using a 10-kG magnet and a 5-ml filter column, 50 million cells were fractionated in less than 10 min, with 99% removal of labeled T lymphocytes. The efficiency of the magnetic method is limited at present by the fact that cells that do not have the surface target antigen of interest, and so are not antibody coated, may adsorb a small amount of label nonspecifically. These then have a nonzero chance of being captured in the filter along with the labeled cells.     

Magnetic sorting of leukocytes

Magnetic filtration of surface-labeled cells has been applied to the fractionation of leukocytes in a model system, using a colloidal magnetite reagent to label mouse spleen cells. This reagent was completely free from problems of aggregation or settling. Since the individual submicron particles were invisible under the microscope, cells were not visibly altered by labeling. Viability also was unaffected by either labeling or magnetic filtration. Using a 10-kG magnet and a 5-mL filter column, 50 million cells were fractionated in less than 10 min, with 99% removal of labeled T lymphocytes. The efficiency of the magnetic method is limited at present by the fact that cells that do not have the surface target antigen of interest, and so are not antibody coated, may adsorb a small amount of label nonspecifically. These then have a nonzero chance of being captured in the filter along with the labeled cells.     

Radiobiology of irradiated leukocytes

Summary The paper continues a series of the author's investigations regarding the determination of certain biochemical and biophysical parameters of the leukocytes taken from animals internally irradiated with³²P. The parameters determined here are the respiratory capacity of PMN leukocytes from Wistar rats submitted to 1 and 2 Ci/g³²P internal irradiations, the proteolytic power and the level of the microelements Zn, Cu and Mn in the same cells and under identical irradiation conditions.The results show a diminished consumption of oxygen only during phagocytosis, a maximum diminution of the proteolytic activity of leukocytes at the 12th day of internal irradiation and a decreasing tendency of Zn, Cu and Mn amounts in leukocytes of irradiated animals, most prominently appearing in the case of Mn.Dedicated to Prof. Dr. Dr. h. c. B. Rajewsky on the occasion of his 80th birthday.     

Orcein staining of leukocytes

An Orcein staining method has been developed which stains mature and immature leukocytes in blood films and bone-marrow smears. Two different patterns of staining are obtained depending upon whether staining is or is not preceded by oxidation. In the latter case, all granulocytes and some monocytes show granular reddish-brown cytoplasmic staining. When prior oxidation is used, the staining is in the form of fine grey or black cytoplasmic granules. All lymphocytes, by both techniques, are negative. It is suggested that Orcein stains sulphated mucosubstances, possibly chondroitin sulphate, which in granulocytes is concentrated in their primary granules.     

The motor of leukocytes

The movements of leukocytes involve extension, flow, and contraction of a margin of organelle-excluding cytoplasm. Actin is the principal structural component of this region. This paper reviews evidence that the expansion of cortical cytoplasm can result from the growth of actin polymers into an orthogonal network in which actin fibers branch perpendicularly under the influence of actin-binding protein. Flow occurs when actin filaments are disassembled and severed. The assembly and fragmentation of actin are regulated by actin-modulating proteins such as profilin, which sequesters actin monomers, acumentin, which binds to the slow-growing end of actin fibers, and gelsolin, a calcium-regulated protein that binds to the fast-growing end of actin polymers and severs actin filaments. Contraction of the actin network is caused by myosin, the assembly and activity of which are regulated by its state of phosphorylation, which is in turn controlled by phosphorylating and dephosphorylating enzymes and by calmodulin and calcium. Present information leads to the prediction that intracellular calcium gradients guide cytoplasmic movement and that the direction of actin assembly and therefore of cytoplasmic extension is toward regions of low cytoplasmic free calcium.