Biomedical subjects
Publications and source records attributed to H Cottier.
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In the absence of serum and its components, zymosan, together with 2-mercaptoethanol present in the medium, stimulated the in vitro primary immune response. Zymosan was effective at a concentration of as low as 2.5 microgram/ml. Removal of macrophages using iron powder resulted in higher recoveries of plaque-forming cells in the presence of zymosan but not of fetuin. Since insoluble zymosan may be easily removed from the culture, the test system described might be suitable for the identification of specific control factors secreted by cells during the in vitro immune response.
Three forms of filter technique for measuring random and directional locomotion of leucocytes have been compared: (1) the conventional one filter technique of Boyden (lower surface count method); (2) the two filter system with a lower cell-impermeable filter designed to count the cells at the underside of the upper filter as well as those on the lower filter (two filter count method); and (3) two filter systems counting only cells associated with the lower filter (lower filter count method). In some instances all three methods produce qualitatively similar results. In others totally different results are reproducibly obtained with identical cell preparations, media and attractants. Compared to the two filter count method, the lower surface count method and the lower filter count method are not sufficiently reliable. The discrepancies are partly due to errors in measuring the response. They are caused by variable cell adhesion to the filters resulting in a varying distribution of cells between the upper and lower filter and/or detachment of neutrophils from the upper filter. Some of the discrepancies are not due to errors in assessing the response, but to differences in gradient formation and drift of chemokinetic and chemotactic materials from one compartment to the other.
A total of ten major lymph node stations have been studied in ICR-strain mice at various time intervals between birth and the age of four weeks. Comparison of lymph node volumes and of volume changes during the observation period revealed that the mesenteric lymph node (MLN) complex was larger at birth and grew at a faster rate than all other nodes. A distinct numerical increase of cortical lymphocytes in MLN at the end of the first week of life was interpreted to be the result of both immigration of T cells and moderate local proliferation, while the quantitatively more important second phase of growth at the age of between two and three weeks might be the consequence of local lymphocyte production. The comparatively modest changes in lymph nodes removed from the gut (axillary and popliteal nodes) could be explained as being due in large measure to immigration of lymphocytes originating in gut-associated lymphoid tissues (GALT).
Cervical, axillary, cubital, inguinal, popliteal, and mesenteric lymph nodes from subjects of various ages who had died a sudden death were examined histologically. Care was taken to establish by morphometry the proportional distribution in lymph node cross-sections of cortical, paracortical, and medullary areas. In addition, numbers and surface areas of cross-sectioned germinal centres were registered. Important differences related to age and anatomical site of lymph nodes were established by this survey. Germinal centre formation, particularly evident in infants and children, less so in young adults, and often absent in ageing individuals, was most impressive in lymph nodes normally exposed to antigenic stimulation (mesenteric and cervical lymph nodes). Paracortical and medullary areas exhibited a slight but gradual reduction with advancing age. Replacement of lymphatic parenchyma by fat tissue (lipomatous atrophy) was a characteristic of more peripheral lymph nodes usually subjected to little antigenic stimulation, that is, cubital, axillary, and popliteal nodes. It should be emphasised that both age-related and regional differences have to be taken into account in a meaningful functional interpretation of lymph node morphology.
Neutrophils from patients with acute bacterial infections show a marked decrease in random as well as directional locomotion in vitro. The further analysis of the data suggests that defective directional locomotion is due to impaired locomotion and not to impaired chemotaxis. The defect disappeared almost completely with clinical recovery. There was no direct correlation between impaired directional neutrophil locomotion and the proportion of band forms in the neutrophil population. Plasma obtained from patients with acute bacterial infections showed no 'spontaneous' chemotactic activity and immune complex-induced cytotaxin formation was normal in vitro. Neutrophils from 2 patients with viral pneumonia showed normal locomotion.
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In an attempt to study changing patterns of lymphocyte influx from blood into lymph nodes following regional antigenic stimulation, mice were injected with either fluid tetanus toxoid alone or complexed (at equivalence) with isologous antibody. The mean number of lymphocytes inside the basement membrane of cross-sectioned postcapillary venules (PCV) was evaluated as a function of time after antigen injection. 'Lymphocyte load' of PCV (LL/PCV) began to increase within less than a day after antigenic stimulation. The initial increment of LL/PCV values in both primary and secondary responses was greater when complexed rather than fluid antigen was used. Peak values were reached earlier, i.e., at the end of day 2, in presensitized as compared with unprimed animals (day 4). Maximum values of mean LL/PCV did not reflect the magnitude of subsequent antibody production under all experimental conditions. We conclude that changes in the LL/PCV belong to early lymph node reactions following regional antigenic stimulation. The pattern of this particular response may vary according to the type of immunizing agent used and the state of immunity (sensitization) of the animal as well as other factors still to be elucidated.
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Evidence has been presented to show that chemokinesis and chemotaxis of human neutrophil granulocytes can be controlled by distinct cellular mechanisms and by different chemicals. Materials such as human serum albumin or fibrinogen had chemokinetic but no chemotactic properties. Highly purified preparations of serum-derived peptides containing classical anaphylatoxin had detectable chemotactic activity only. Chemokinetic as well as chemotactic substances were required for the expression of chemotaxis in the form of efficient directional locomotion. The roles of chemokinesis and chemotaxis in the regulation of directional locomotion have been analyzed. Further experiments showed that the chemotactic response conforms to the law of Weber-Fechner. The number of cells which had accumulated in response to a chemotactic simulus was proportional to the logarithm of the concentration of the chemical substance. Readaptation from high to low chemotactic stimulus occurred only to a limited extent.
Combined intraperitoneal injection of talc and particulate prednisolone acetate resulted in the formation of significant numbers of multinucleated giant cells within 48 hours. Neither one of these two agents had a comparable effect when injected alone. Evidence is presented showing that the multinucleated giant cells arose by cell fusion. Synchronous nuclear division could be observed in a considerable proportion of newly formed polykarions. Although the late prophases were usually normal, high proportions of abnormal mitotic figures were observed at later stages of mitosis, particularly in anaphase and telophase. The chromosome abnormalities were so severe that it is highly improbable that mitosis led to successful nuclear multiplication within a given syncytium. Similar to prednisolone acetate, prednisone elicited the formation of multinucleated giant cells when injected with talc. No polykarion formation was observed, however, when prednisolone acetate was substituted for other steroid preparations of similar particle size such as cortexon acetate, cortisone, or testosterone isobutyrate.
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Experiments performed by means of time lapse cinematography or the filter technique show that human serum albumin has marked chemokinetic effects on neutrophil cultured in Gey's solution. The average speed of the cells, as well as the proportion of neutrophils showing locomotion, is increased. Enhanced locomotion correlates with decreased attachment to the substratum as determined by morphological and functional criteria.
The effect of chemotactic peptides which lack chemokinetic activity has been investigated. The neutrophil response is proportional to the logarithm of the stimulus intensity, or alternatively a power function with an exponent of 0.3. Equal responses are obtained for equal ratios between the peptide concentration in the lower compartment and the threshold concentration. The significance of Weber-Fechner's law in leucocyte chemotaxis is discussed.