Hans Cottier

The bursa of fabricius: A central organ providing for contact between the lymphoid system and intestinal content

Abstract Small inert particles, after oral or intracloacal administration to chickens, are readily taken up and deposited throughout the medullary portion of bursal follicles. Epithelial tuft cells transporting this material are distinctively equipped with lytic enzymes. No entry of living bacteria into the lymphoid tissue was observed. These findings are indicative of an antigen-driven development of the bursal system protected by local bactericidal mechanisms.

Re-assessment of Boyden's technique for measuring chemotaxis.

Abstract Boydens one-filter technique for measuring chemotaxis of polymorphonuclear leucocytes is based on the assumption that all cells which have migrated through the membrane remain at its lower surface where they are counted. Since a variable proportion of cells on the bottom side of the membrane becomes detached, the one-filter system is not a reliable quantitative method. A modified procedure eliminating this loss of cells by the use of two filters, the lower one being impermeable for leucocytes, is described.

Studies on the regulation of the neutrophil chemotactic response using a rapid and reliable method for measuring random migration and chemotaxis of neutrophil granulocytes

AbstractsAn economic and sensitive test system for measuring random and directional migration of human neutrophils is described. The technique, based on a modified Boyden chamber equipped with a two-filter system, permits a substantial reduction of both incubation time and sample volume. The influence of various technical factors such as the neutrophil concentration in the cell suspension, the incubation time of the chambers, the test concentration of activated plasma or serum, the presence of heparin, and the procedure for separating neutrophils from human peripheral blood, was investigated. Standardized procedures for measuring and reporting neutrophil chemotaxis are proposed.The method has been used to study the significance of factors regulating neutrophil migration such as cytotaxin inactivators and neutrophil immobilizing factors (NIF). Activity of cytotaxin inactivators as assessed in undiluted serum or plasma at pH 7.4, 6.0 or 4.0 was very low. In contrast, potent neutrophil immobilizing activity was found in human serum or diluted plasma. These factors which inhibit migration were accordingly termed neutrophil immobilizing factors of plasma (NIF-P) and neutrophil immobilizing factor of serum (NIF-S). These factors are heat-stable, non-dialysable and of high molecular weight.

Cellular kinetic and phenotypic heterogeneity in and among Burkitt's and Burkitt-like lymphomas.

This study asks whether the known genotypic heterogeneity within and between endemic or sporadic Burkitts lymphomas (eBLs and sBLs, n=10 each), and Burkitt‐like lymphomas (BLLs, n‐12), is reflected in divergent cytokinetics and related immunophenotypes. There was strong evidence that eBL and BLL grow markedly faster than sBL, as shown by differences in mitotic and apoptotic indices. Furthermore, in BLL, the median percentage of neoplastic cells immunoreactive for the bcl‐2 protein was much higher than that observed in eBL and sBL. The reverse was true for the median fraction of cells containing c‐myc protein. In eBL and sBL, the median fraction of bcl‐6 protein‐positive cells reached values above 50 per cent, while cells of 8/12 BLLs did not contain detectable amounts of this protein. This observation indicates that in this respect, eBL and sBL resemble normal germinal centres of lymphatic tissue much more than do BLL. Evidence for infection of neoplastic cells by the Epstein‐Barr virus (EBV) was observed in 9/10 cases of eBL and in 3/10 of sBL, but not in BLL. EBV‐positive lymphomas were associated with distinctly lower apoptotic indices and smaller median percentages of bcl‐6‐positive cells than EBV‐negative tumours.

Congenital "histiocytoid" cardiomyopathy: evidence suggesting a developmental disorder of the Purkinje cell system of the heart.

The so-called “histiocytoid cardiomyopathy” is an unusual cardiac disorder of infancy and childhood, characterized by the presence of numerous foamy, lipid-containing cells between the endocardium and the striated myocardial cells of the left ventricle and the interventricular septum. The disease usually affects females, the clinical picture being dominated by severe disturbances of conduction. The original designations of the disorder stem from the morphological resemblance of the foamy cells to lipid-laden histiocytes. However, subsequent investigations have shown these cells to contain myofibrils interposed with Z lines. It has, therefore, been suspected that the leading cell population might be related to the myocardium. Using a histochemical method for the demonstration of cholinesterase activity in the foamy cells, we present evidence that “histiocytoid” cardiomyopathy may in fact correspond to a maldevelopment of the Purkinje cell system of the heart.

The chemokinetic effect of serum albumin.

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 Geys 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.

FATE OF THYMOCYTES: STUDIES WITH 125I-IODODEOXYURIDINE AND 3H-THYMIDINE IN MICE

Cortical thymocytes of young adult mice were labeled in situ with radioactive DNA precursors. As a result of cell emigration and cell death, total thymic radioactivity decreased within 8 days to 10% or less of that present on day 1. Accumulation of thymic migrants in peripheral lymphoid organs was estimated by computing the net thymus‐derived radioactivity in these tissues. Thymic cell death was assessed by comparing values obtained with 125I‐UdR to those acquired with 3H‐TdR. The results indicate that cortical thymocytes migrate to the spleen, mesenteric lymph node, femurs and intestine; nevertheless, only a small fraction of the activity originally present in the thymus was recovered in these organs; the vast majority of newly formed cortical thymocytes apparently die after a relatively short life span. Exclusive of the fraction which dies in situ, evidence for thymocyte death is seen in bone marrow; however, most migrants appear to terminate in the intestine.

Kinetics of Cellular Death in Germinal Centers of Mouse Spleen

Continuous cell death is a phenomenon inherent to germinal centers of lymphoid tissue, as well as to other rapidly proliferating somatic cell systems. Its significance, if any, is unknown.

Nonspecific esterase in human lymphocytes.

A substantial proportion of human peripheral lymphocytes exhibits esterase activity as demonstrated by cytochemical techniques using hexazotized pararosanilin as coupling agent and different alpha-naphthyl compounds, in particular alpha-naphthyl-acetate, as substrates. Esterase-positive lymphocytes showed one or several dots of the reaction product. Plasma cells and macrophages also exhibited marked esterase activity but with diffuse distribution of the reaction product throughout the cytoplasm. The substrate specificity, the time course and the pH optimum of the cytochemical reaction were determined. The results indicate that these lymphocyte esterases are identical with acid lipases. The number of esterase-positive cells reaches a plateau well below 100% (85% for blood lymphocytes) even with optimal staining procedures. The relation between esterase activity and other so-called lymphocyte markers such as sIg and the capacity to form spontaneous rosettes with sheep red blood cells was investigated in peripheral human blood lymphocytes. A fair correlation between rosette formation and esterase activity was found and most of the esterase-positive cells were sIg-negative. However, the fit was never complete. The results suggest that esterase activity is largely characteristic for small peripheral T cells. Almost all blast cells formed following stimulation with Con A or PHA were esterase-positive. Histochemical studies showed that the large majority of the thymocytes in the cortex lacked esterase activity. In lymph nodes, a low proportion of esterase-positive cells was found in the germinal centers, whereas most lymphocytes in the paracortical are were esterase-positive.

The filter technique for measuring leucocyte locomotion in vitro. Comparison of three modifications

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.