Assuntos

Assuntos

RESUMO

To investigate the significance of mast cells in the popliteal lymph node during the development of an inflammatory response, rats were inoculated with 12 x 10(7) colony-forming units of Staphylococcus aureus in the hind foot pad. Numerical changes in mast cells were then measured in the corresponding popliteal lymph node. Six days after inoculation, despite the enlargement of the responding lymph node, a marked decrease in granulated mast cell number, relative to the contralateral node, was observed in the cortical and medullary compartments. Popliteal lymph nodes from rats treated with compound 48/80 and then inoculated with S. aureus showed a higher cortical and medullary hypertrophic response and a significant increase in degranulated/weakly basophilic mast cell number in the lymph node tissue. The findings suggest that (1) Staphylococcus aureus induces a reduction in granulated mast cell number in the cortical and medullary compartments of regional lymph nodes; (2) pretreatment with compound 48/80 appears to contribute to the lymphoid cell proliferation and the hypertrophic response of lymph nodes induced by S. aureus; and (3) granulated mast cells have a regulatory role on lymphoid cell proliferation.

Assuntos

RESUMO

The cloacal bursa is a primary lymphoid organ responsible for the maturation of B-lymphocytes. It has been suggested that the bursa may also play a peripheral role when antigens are inoculated by cloacal route. Qualitative and quantitative structural modifications in the bursa from chicks inoculated with Bordetella pertussis by the cloacal route were investigated. Observations indicated that the relative bursal growth as well as the volume fraction and the mitotic index of the follicular medulla from experimental bursae are significantly greater than those of the controls. Macrophages which have phagocytized bacteria, and a gradual relative increase of the RER of lymphoblasts, were other structural modifications found exclusively in the follicular medulla. The observations suggest that the bursal follicular cortex and medulla act as autonomous histophysiological compartments, the latter being responsible for an antigenic stimulation when Bordetella pertussis is intracloacally inoculated in chicks.

Assuntos

RESUMO

Neuropeptides have been shown to modulate the bidirectional communication between the central nervous and immune systems. The endooligopeptidase (EC 3.4.22.19), originally isolated and characterized in the nervous tissue, was shown to hydrolyse several neuropeptides and to generate enkephalin from enkephalin-containing peptides. This report shows the presence of endopeptidase 22.19 in the rat immune system using both biochemical and immunochemical methods. The specific activity of endopeptidase 22.19 in soluble fraction of lymphocytes was 3-4-fold higher than the one found in the nervous tissue. Among rat blood cells the highest specific activity of endopeptidase 22.19 was found in T lymphocytes, being 2.5-fold higher than the activity found in other leukocytes. Immunocytochemical studies performed in tissues and cells of the immune system indicate the presence of endopeptidase 22.19-like enzyme in all types of leukocytes. The occurrence of this enzyme in cells of the immune system can be considered an important step in understanding the metabolism of neuropeptides in the immune system as well as its possible participation as a regulatory enzyme in neuroimmunomodulation.

Assuntos

RESUMO

The estimated volumes of the follicular medulla (x) and cortex (y) from 14-day-old embryos till 28-day-old White Leghorn chicks were associated through the allometric formula y = bxk or log y = log b + k log x. Two successive allometric growth stages (I and II) are discernable, being hatching the transition region between them. The volumetric growth of the cortex is 2.49 times greater than that of the medulla in stage I, whereas cortex and medulla grow isometrically in stage II. The curve fitting procedure analysis of the absolute cortical and medullary growth confirmed these results. The fine structure of the cell types in the follicular medulla revealed that: a) in the allometric stage I pre-existing, bud precursor (Pr) cells appear to give rise to basal (Ba) and medullary epithelial (ME) cells, in both cases showing lucent and dark varieties. A medullary cytoreticulum is established at the onset of this stage. b) The marked lymphocyte proliferation during stage II occurs among the thin and short cytoplasmic processes of BA cells. These processes extend towards the centre of the medulla and also show many lateral interdigitating processes. During this same stage, the cytoplasmic processes of ME cells elongate and become thinner promoting a widening of the cytoreticulum interstices. The fine structural analysis of the cortical cytoarchitectural arrangement showed that: a) before the onset of stage I (14-day-old embryos) the cortex consists mainly of typical fibroblasts (F) and a few blastic (Pr?) cells. Later in this stage I, a poorly defined cortical framework is made up of typical fibroblasts, few cortical branching (CB) cells of the epithelial variety (which seem to be derived from Pr cells) and CB cells of the fibroblast-like variety. These cells are interspersed with mature and immature lymphocytes. b) Allometric stage II of the cortex is characterized by the presence of very thin and long cytoplasmic processes from CB cells of both epithelial and fibroblast-like varieties. The arrangement of CB cell profiles, visualized in electron micrographic montages, is remarkably similar to that of the ME cells profiles which are known to form a cytoreticulum. We thus propose that the mature follicular cortex is endowed with a cellular framework forming wide interstices in which packed mature lymphoid cells are lodged.

Assuntos

RESUMO

The allometric relation between the increment of the body weight and the relative growth of the cloacal bursa shows that the bursal growth is greater than the body growth, during the period analysed (from the 16th d of embryonic development through the 28th post-hatched day). No statistical difference in the mean relative bursal weight between male and female birds was achieved in the above mentioned period analysed. The advantages of using an allometric study for the evaluation of an organ's growth during development are discussed.

Assuntos

RESUMO

The allometric relation applied between the body weight and the volume increment of the interfollicular surface epithelium (ISE) showed just one developmental stage during the period analysed (from 16d old embryos through 28 old d chicks). In this single allometric developmental stage the ISE growth is relatively more pronounced than that of the bursa as a whole due to profound cellular modifications which that epithelium undergoes from the primitive undifferentiated epithelial cells through goblet and prismatic cells. The latter could have an endocytic capability due to their primary and secondary lysosomes content. A possible cellular differentiation of the ISE during the histogenesis of the cloacal bursa is also discussed.

Assuntos