The isolation and properties of the specific cytoplasmic granules of rabbit polymorphonuclear leucocytes

A method has been described for isolation of the specific cytoplasmic granules of rabbit polymorphonuclear leucocytes. Homogeneous suspensions of leucocytes were disrupted by lysis in 0.34 M sucrose. This procedure liberated the cytoplasmic contents of the cell and dissolved a considerable proportion of the nuclei. Following disruption, the sucrose lysate was separated into three fractions by differential centrifugation, i.e. 400 g or nuclear pellet, 8,200 g or granule pellet and the postgranule supernate. Microscopic examination revealed that the 8,200 g pellet was composed of intact granules as well as occasional mitochondria. The other two fractions were morphologically heterogeneous. Studies with isolated granules demonstrated their lysis by a variety of weak acids and surface-active agents. When buffered solutions were employed between the ranges of pH 2.0 and 9.0, granule lysis began at pH 5.5 and was complete at pH 4.0. Chemical analysis disclosed that the granule pellet contained protein and phospholipid with only traces of nucleic acids. Approximately 70 to 80 per cent of the total cellular antimicrobial agent phagocytin was present in the granule fraction. This material was liberated from the granules by acid (pH 5.0 or lower). Studies on selected enzymes showed that acid phosphatase, alkaline phosphatase, nucleotidase, ribonuclease, deoxyribonuclease, and beta glucuronidase were predominantly localized in the granule fraction. Approximately 50 per cent of total cellular lysozyme and cathepsin were also present in the 8,200 g pellet. Disruption of the granules was associated with the release of the majority of granule protein and enzymes in a non-sedimentable form. The properties and composition of rabbit polymorphonuclear leucocyte granules seem to be analogous to those of liver lysosomes.

A histochemical study of phagocytic and enzymatic functions of rabbit mononuclear and polymorphonuclear exudate cells and alveolar macrophages. I. Survey and quantitation of enzymes, and states of cellular activation

The cytochrome oxidase (CO), aminopeptidase (AMP), succinic dehydrogenase (SD), acid phosphatase, esterase, and alkaline phosphatase of rabbit mononuclear (MN) and polymorphonuclear (PMN) peritoneal exudate cells and pulmonary alveolar macrophages (AM) - air dried on Mylar strips - were characterized by histochemical techniques with respect to stability, activators, inhibitors, and pH optima. A granule count method was established for the quantitation of these enzymes. For the acid phosphatase of MN, in which the most precise results were obtained, time, pH, substrate, and inhibitor curves resembled those commonly obtained biochemically. Five of these enzymes were usually more active in AM than MN, whereas the sixth, alkaline phosphatase, was not present in either cell type. AM also tended to consume more oxygen than MN and to divide more frequently. Since the most active cells in the population would be first involved in the host's defense against microbial agents, a comparison was made of the 10 per cent of the AM and MN with the highest enzymatic activities. No differences were found in the granule counts that were not reflected by the means. However, within a given AM population, cells containing ingested dust particles seemed to have higher enzymatic activities than those without particles. MN had greater acid phosphatase and SD activities than PMN and consumed more oxygen, but the CO, AMP, and esterase activites of both types of cells were of similar magnitude. PMN showed high alkaline phosphatase activity; MN showed none. A survey of the histochemical literature indicates that a positive correlation between the enzymatic and phagocytic activities of both MN and PMN exists in vivo.

Heterochromatin in human male leukocytes

Tritiated thymidine was added to peripheral blood cultures containing phytohemagglutinin so that DNA synthesis in interphase nuclei of white blood cells in the human male could be studied. After 57 hours in culture, a large heterochromatic body with a central position is seen in unlabeled Feulgen-stained nuclei. In labeled nuclei in which DNA synthesis was taking place in both the eu- and heterochromatin at the time the thymidine became available, the heterochromatin shows a higher number of silver grains per unit area, accompanied by a stronger Feulgen reaction, an indication of its higher DNA content. The time of DNA synthesis in the heterochromatin blocks is different from that in the surrounding euchromatin. The large heterochromatic block is composed of chromosome segments gathered together around the nucleolus but it is not part of this organelle. In preparations stained with azure A and acid fuchsin for demonstrating both the nucleolus and the chromosomes, six distinctly heteropyenotic chromosome segments can be seen associated with the nucleolus. Cells of all size categories were found to incorporate tritiated thymidine. The distinct appearance of autosomal heterochromatin in white blood cells may be the result of the new physiological conditions to which the cells are subjected in the medium containing phytohemagglutinin.

The fate of bacteria within phagocytic cells. I. The degradation of isotopically labeled bacteria by polymorphonuclear leucocytes and macrophages

The intraleucocytic fate of a variety of P³²- and C¹⁴-labeled bacteria has been studied in both polymorphonuclear leucocytes and macrophages. Both cell types brought about extensive degradation of bacterial lipids, nucleic acids, and proteins. Intracellular breakdown was primarily dependant upon the composition of the ingested particle rather than on the type or source of the phagocyte. Evidence is presented for the reincorporation of bacterial constituents into leucocyte lipid. More than 50 per cent of the acid-soluble degradation products of P³²-labeled bacteria appear as inorganic phosphate. Bacterial RNA is degraded more readily than DNA. Following phagocytosis, labeled bacteria lose their pool of small molecular weight intermediates. This is followed by the degradation of acid-insoluble constituents. The majority of bacterial breakdown products are then excreted by the leucocyte and appear in the medium. Heat-killed bacteria were more readily broken down than viable organisms. Only small amounts of C¹⁴-labeled bacteria were completely oxidized by leucocytic enzymes to C¹⁴O₂. Acid extracts of polymorphonuclear leucocyte granules, which were highly bactericidal, liberated the acid-soluble constituents of labeled bacteria but did not significantly degrade bacterial macromolecules.

Further observations on the behavior of staphylococci within human leukocytes

A specific serum factor was required for rapid phagocytosis of pathogenic staphylococci by human polymorphonuclear leukocytes when the ingestion process was studied in siliconed glass systems and the concentrations of staphylococci were maintained at low levels. In contrast to certain other microbes, the resistance to phagocytosis which characterized pathogenic staphylococci was relative, and phagocytosis was readily accomplished when large populations of staphylococci were present in the test system. A factor promoting phagocytosis was present in eight of eight normal adult sera. In contrast, the sera of twenty-eight of thirty normal rabbits did not promote phagocytosis. Serum obtained from 2 rabbits maintained in the rabbit colony for several months acquired the ability to opsonize pathogenic staphylococci. The phagocytosis-promoting factor was almost completely removed by prior absorption of test sera with the homologous strain. The factor was incompletely removed by absorption with heterologous strains of pathogenic staphylococci and was not significantly reduced by absorption with coagulase-negative staphylococci or unrelated microorganisms. Present evidence suggests that the factor promoting phagocytosis is a thermostable opsonin. While the activity of heated serum could not be restored by the addition of small amounts of fresh serum or complement, the addition of large amounts of complement partially restored opsonic activity. Incubation of staphylococci in fresh serum prior to heat inactivation did not reduce subsequent phagocytosis, further suggesting the heat stability of the phagocytosis-promoting factor. Preliminary studies correlating the presence of antistaphylococcal hemagglutinins and phagocytosis-promoting factor in certain sera suggest that the two factors were not necessarily related. The phagocytosis of staphylococci in fresh human serum was inhibited by the addition of fresh or inactivated rabbit serum. Further studies on the nature of such inhibition are in progress. Once ingestion was accomplished, coagulase-positive staphylococci consistently survived in significant numbers within the cytoplasm of human granulocytes. Coagulase-negative staphylococci appeared to be destroyed within the leukocyte and could not be recultured from the cytoplasm following 3 to 4 hours of intracellular residence.

Tuberculin hypersensitivity: studies with radioactive antigen and mononuclear cells

The type and fate of mononuclear cells of guinea pigs hypersensitive to tuberculin were studied by means of purified protein derivative labeled with I(125) and mononuclear cells labeled with tritiated thymidine. Purified protein derivative labeled with I(125) was taken up in vitro by lymphocytes and neutrophils from animals that were either sensitive or nonsensitive to tuberculin, but it was bound more frequently by the cells of sensitive animals. Passive transfer of tuberculin hypersensitivity by means of lymphocytes labeled with tritiated thymidine indicated that significant numbers of radioactive cells migrated to the site where the skin was tested with purified protein derivative only when the test was made immediately after transfusion. Although skin reactions from tests made with purified protein derivative 24 hours after transfusion were comparable to those from tests made immediately, the number of labeled cells at the sites of the later tests was not consistently larger than it was in controls (Histoplasmin reactions). Thus transfused tuberculin-sensitive cells are neither always attracted to the sites of the test with purified protein derivative nor are they required in large numbers at the site for a positive reaction to develop.

Metabolic patterns in three types of phagocytizing cells

Some chemical and metabolic characteristics of polymorphonuclear leukocytes and monocytes from peritoneal exudates of the guinea pig, and of alveolar macrophages from the same animal, have been compared. Changes in the metabolic patterns of these three types of cell have been followed during the act of phagocytosis. The effect of conventional inhibitors of metabolism, and of anaerobiosis on the phagocytic ability of each of the three cell types mentioned has also been determined. From these studies it was found that alveolar macrophages depend to a considerable degree upon oxidative phosphorylation to provide energy for phagocytosis. The other two types of cell depend only on glycolysis as the source of metabolic energy for that function. In some experiments aimed at obtaining information on the possible role of complex lipids in the function of the cell membrane, it was noted that phagocytosis stimulated the incorporation of inorganic phosphate-P³² into the phosphatides of both types of cell from peritoneal exudates—whether these were free-swimming or adherent to a surface. This phenomenon has not yet been detected in the case of alveolar macrophages.

In vitro studies of ulcerative colitis. II. Cytotoxic action of white blood cells from patients on human fetal colon cells

Freshly isolated fetal human colon cells were labeled with (32)P-orthophosphate or (14)C-amino acids and exposed to white blood cells from children with ulcerative colitis or from healthy controls. Exposure of the colon cells to patients' white cells led to a rapid isotope release, significantly higher than that obtained with normal white cells. After 150 minutes of incubation, 75 per cent of the total isotope present was found in the media of the colitis samples but only 40 per cent in those of the controls. Consistent results were obtained with white blood cells from 14 patients and 18 healthy individuals. Similar results were obtained with either fresh white cells or with white cells aged for 12 to 18 hours and consisting to 60 to 70 per cent of lymphocytes and to 20 to 30 per cent of large mononuclear cells. No specific cytotoxic activity could be conferred onto normal white cells by pretreating them with patients' serum containing antibodies against colon antigen. The cytotoxic action of the patients' white cells was immunologically specific, since no difference from the controls was found in the isotope release when cells from other organs or animals were similarly treated. Preliminary experiments suggested that the patients' white cells could be desensitized by pretreating them with colon extract. For obtaining a significant cytotoxic effect of the patients' white cells, the presence of 10 to 20 per cent of fresh guinea pig or human serum in the incubation medium was required.