In vitro synthesis of antimycobacterial antibodies with different specificities in various tissues of leprosy patients.

For the detection of the synthesis in vitro of anti-Mycobacterium leprae antibodies in various tissues of leprosy patients, biopsy specimens of skin lesions, nasal mucosa, larynx, lymph nodes, and bone marrow were cultured in a medium containing 14C-labeled lysine and isoleucine. The culture fluids were analyzed by crossed immunoelectrophoresis with intermediate gel and autoradiography. The results show that synthesis of anti-M. leprae antibodies occurs at the investigated sites of leprosy patients and that the specificities of the synthesized antibodies differ between sites in individual patients. It is conceivable that these antibodies play a role in the local defense against M. leprae.

In vitro synthesis of immunoglobulins in cutaneous leishmaniasis.

In an in vitro study, IgG was synthesized in large amounts by tissue from cutaneous leishmaniasis lesions. IgA and IgM were produced in the minority of the cultures in distinct and small amounts, respectively. Synthesis of complement (C3 and C4) could not be detected, but lysozyme was produced sporadically. The significance of these findings is discussed.

Cell kinetic analysis of a murine macrophage cell line.

For the present study, which was performed to find a reliable method suitable for determination of the cell kinetic parameters of a continuous cell line, use was made of the macrophage cell line J774.1. The doubling time of the cell population was approximately 27 h. The continuous labeling curve showed that all the cells divide and almost no quiescent cells occur. The cell-cycle time as determined from the curve of the labeled cells in mitosis, the course of the stathmokinetic index, and time-lapse videorecordings, was about 19 h. The discrepancy between the population doubling time and the cell-cycle time must be due to death and disintegration of cells during culture in vitro. The results indicate that the doubling time of a cell population is not a reliable parameter to determine the kinetics of a population of continuously proliferating cells and that determination of the course of the stathmokinetic index offers a rapid and simple method to establish the cell-cycle time reliably.

The characterization, origin, and kinetics of skin macrophages during inflammation.

This report deals with the characterization, origin, and kinetics of exudate skin macrophages. The inflammatory stimulus used was a subcutaneously inserted glass coverslip. The macrophages adhering to the glass surface have many characteristics in common with circulating monocytes. During this kind of inflammation there is little differentiation into a more mature or activated type of mononuclear phagocyte. The kinetic studies with [3H]thymidine as cell marker and calculation of local production at the site of inflammation as well as the influx of cells to that site led to the conclusion that greater than or equal to 99% of the exudate skin macrophages were monocyte derived and less than or equal to 1% originated by local division of macrophages.

Dual origin of mouse spleen macrophages.

The present study concerns the isolation, characterization, origin, and kinetics of spleen macrophages. The spleen was first perfused in situ to remove monocytes from the vascular bed and then dissected and treated with collagenase. The macrophages in the cell suspension thus obtained were characterized morphologically and cytochemically and then quantitated. The spleen cell suspension was incubated for 24 h in Leighton tubes to obtain an enriched glass-adherent population of macrophages for characterization and [3H]thymidine-labeling studies. Almost all of the adhering macrophages were esterase positive, had Fc and C3b receptors, and ingested EIgG and opsonized bacteria. In vitro labeling with [3H]thymidine showed that approximately 5% of the mononuclear phagocytes in the spleen synthesize DNA and must be considered to be dividing cells. The course of the number of labeled monocytes and macrophages after a single injection of [3H]thymidine indicates migration of monocytes into the spleen, where they become macrophages. Calculation of the influx of monocytes into the spleen and of the local production of macrophages by DNA-synthesizing mononuclear phagocytes showed that under steady-state conditions, 55% of the population of spleen macrophages is supplied by monocyte influx and 45% by local production. This means that there is a dual origin of spleen macrophages. The mean turnover time calculated with the value for the efflux of spleen macrophages is 6.0 d.

Micro-CO2-incubator for use on a microscope.

A simple micro-CO2-incubator designed for use on the stage of an inverted microscope is described. This micro-incubator is easy to use, offers a handy tool for the culture of cells under the microscope and its performance compares well with that of a conventional CO2-incubator. A standard disposable culture dish can be placed in the micro-incubator. The culture medium is covered by a gas-permeable layer of mineral oil, this protects the culture from the environment without affecting the culture conditions and allows easy cell manipulation under microscopical control.

Characterization of mononuclear phagocytes from the mouse, guinea pig, rat, and man.

The present paper describes cytochemical, membrane, functional, and mitotic characteristics of monoblasts, promonocytes, monocytes, and macrophages of the mouse, guinea pig, rat, and man. For all of these species the results show that after staining for nonspecific esterase, with alpha-naphthylbutyrate as substrate, and for lysozyme, mononuclear phagocytes can be distinguished from other cells, e.g., T and B lymphocytes. However, it must be kept in mind that immature and mature granulocytic cells are also lysozyme positive. The presence of Fc and C receptors is dependent on the maturity of the cells and the duration of incubation in vitro; with respect to the former, an in vivo population of immature mononuclear phagocytes may have a lower percentage of positive cells than is the case in a mature population, and with respect to the latter, the percentage of positive cells rises during incubation. Phagocytosis of opsonized bacteria and red cells is a reliable criterion for the distinction between mononuclear phagocytes and other cell types, e.g. lymphocytes and fibroblasts. In all of the species studied, the majority of both immature and mature mononuclear phagocytes ingested particles opsonized with IgG; the proportion of phagocytosis of red cells via C3 receptors is usually very small. Incorporation studies with [3H] thymidine have shown that immature mononuclear phagocytes (i.e., monoblasts and promonocytes) divided and that monocytes and macrophages do not. The small number of macrophages that incorporate [3H] thymidine are immature mononuclear phagocytes which have very recently arrived in the tissues from the bone marrow. Comparison of mononuclear phagocytes in different organs of various species has shown unequivocally that these cells belong to one cell line, called the mononuclear phagocyte system.

Comparison of the in vivo and in vitro proliferation of monoblasts, promonocytes, and the macrophage cell line J774.

Mononuclear phagocytes are localized in the bone marrow compartment (monoblasts, promonocytes and macrophages), the circulation (monocytes), and the tissues and serous cavities (macrophages). In vivo and in vitro studies done in murine bone marrow have shown that monoblasts and promonocytes are the most immature, dividing cells of the mononuclear phagocyte cell line; monocytes and resident macrophages do not divide. A very small percentage of the mononuclear phagocytes in the tissues, which are bone-marrow derived and have already the morphology of macrophages, divide once in vivo. The progeny of these dividing cells contribute to the maintenance of the tissue population of macrophages under steady-state conditions. In vitro an appreciable percentage of (young) macrophages divide, in all probability due to the influence of colony-stimulating factor. The cells of macrophage cell lines are transformed cells that proliferate continuously. The morphological, cytochemical and functional characteristics of all these kinds of cells, as well as their proliferative behavior in vivo and in vitro, show great similarity, although there are also distinct differences.

Method to prove investigation of particles by macrophages with light microscopy.

Research on phagocytosis is often hampered by the inability to distinguish whether (opsonized) particles have been ingested by phagocytes or are only attached to the surface of these cells. Treatment of the cells after phagocytes to remove all extracellular particles makes it possible to evaluate phagocytosis with certainty by light microscopy. Opsonized erythrocytes attached to the macrophage surface are usually removed by hypotonic lysis. The present report describes the advantages of the use of lysostaphin to lyse Staphylococcus aureus and of xylene, chloroform or dioxane to dissolve polystyrene latex beads on the surface of peritoneal macrophages and embryonic fibroblasts. This procedure facilitates differentiation between professional and facultative phagocytes.

The origin, kinetics, and characteristics of the Kupffer cells in the normal steady state.

Enzymatic digestion with pronase and DNAase was used to isolate Kupffer cells from mouse liver. The characteristics of these cells were found to be similar to those of peritoneal macrophages, except that in the initial suspension the percentage of Kupffer cells with Fc receptors was low, C receptors were absent and the ingestion of opsenized bacteria was very poor, because of the effect of pronase on the cell membrane. After 24 h incubation in vitro all these characteristics return. The in vitro and 1 h-pulse [(3)H]thymidine labeling of the Kupffer cells is low (0.8 and 1 percent, respectively) indicating that in essence these cells do not divide. It was also shown that the small percentage of in vitro labeled Kupffer cells was recently derived from the circulation. After an intravenous injection of zymosan the in vitro labeling index of the Kupffer cells increased 16-fold, but it was proven that these dividing cells were immature mononuclear phagocytes very recently recruited from the bone marrow. The labeling of Kupffer cells aider one or four injections of [(3)H]thymidine reached a peak of 10.4 percent at 48 h or 24.1 percent at 60 h, respectively, indicating that these cells are derived from labeled monocytes. Further evidence for this conclusion was obtained by the absence of an increase of labeled Kupffer cells during treatment with hydrocortisone, which causes a monocytopenia during which no circulating monocytes are available to migrate to the tissues. Labeling studies in animals X-irradiated with hind-limb shielding gave a Kupffer cell labeling index of 5-10 percent of the normal values, which confirms their bone marrow origin. A quantitative study on the production of labeled monocytes in the bone marrow and their transit through the circulation showed that in the normal steady state at least 56.4 percent of the monocytes leaving the circulation become Kupffer cells. Considering the Kupffer cells as kinetically homogeneous this gives a mean turnover time of the total population of Kupffer cells of 21 days.

The effect of azathioprine (Imuran) on the cell cycle of promonocytes and the production of monocytes in the bone marrow.

The present communication concerns the effect of azathioprine on the mitotic activity of promonocytes and the production of monocytes. In vitro and in vivo labeling with [3H]thymidine showed that during azathioprine treatment the promonocytes synthesize DNA and that, contrary to expectation, the labeling index increases. Cytospectrophotometric determination of the Feulgen-DNA content of the promonocytes during azathioprine treatment showed an increase in the percentage of tetraploid promonocytes, and determination of the various phases of the cell cycle showed significantly increased DNA synthesis and cell cycle times as compared with the normal steady state. On the basis of these results it can be concluded that azathioprine arrests the cell cycle of the promonocytes late in the DNA synthesis phase or in the postsynthesis (G2) phase and mitosis does not occur. This timing of the effect of azathioprine had not been previously observed. The diminished mitotic activity of the promonocytes during azathioprine treatment depressed monocyte production. During treatment with 3 mg/kg azathioprine the cell cycle time of the promonocytes was on the average 5.5 h longer than in the normal steady state and the rate of monocyte production was reduced by 70%. During an acute inflammatory reaction too, monocyte production is affected by azathioprine. In animals not treated with azathioprine but with an acute inflammation the cell cycle time becomes shorter and the monocyte production increases, but animals treated with (3 mg/kg) azathioprine do not show this effect. The kinetics of the monocyte also changes under the low dosage of azathioprine. As consequence of the diminished production of monocytes, far fewer (about 50%) monocytes enter and leave the circulation than during the normal steady state. During an acute inflammatory reaction the numbers in transit through the circulation are slightly augmented but remain considerably lower than in nonazathioprine-trehat of animals not treated with azathioprine.

The kinetics of promonocytes and monocytes in the bone marrow.

The mononuclear phagocytes of the bone marrow can be classified into two cell types, promonocytes and monocytes. The present study was performed to establish whether the promonocytes are the progenitors of the monocytes and to determine the kinetic characteristics of the promonocytes and monocytes in the bone marrow compartment. Both in vitro labeling studies with thymidine-(3)H and determination of the relative amount of DNA in the nuclei of individual cells showed that under normal steady-state conditions the promonocytes are proliferating cells and the monocytes, nondividing cells. In vivo labeling studies provided further evidence that the promonocytes are the progenitor cells of the monocytes. During the first 24 hr after labeling, the promonocytes showed a constant high level of labeling (about 70%). The mean grain count of these cells decreased with time. The labeling index of the monocytes of the bone marrow increased during the first 24 hr after in vivo labeling, but during the same period the mean grain counts remained almost constant, with values amounting to about half those of the promonocytes during the first 6 hr of the experiment. The data concerning the labeling indices and the percentage distribution ratio of the promonocytes and monocytes in the bone marrow, and the labeling indices of the peripheral blood monocytes are used to construct a model population. The results lead to the conclusions that the promonocytes are multiplicative cells and that both daughter cells arising from the division of a promonocyte are monocytes. The DNA-synthesis time found for the promonocytes is 13.6 hr. From this value, the average generation time was computed to be 19.5 hr.