Pericapillary spongy sheaths in the human spleen. An immunohistological study

The role of reduced red cell deformability in the pathogenesis of severe falciparum malaria and its restoration by blood transfusion

As reduced red cell deformability (RCD) can contribute to derangement of the microcirculation, a central feature in the pathogenesis of severe malaria, RCD was measured with a laser diffraction technique in 232 consecutive patients with falciparum malaria on the Kenyan coast, of whom 99 had severe disease. RCD on admission (measured as elongation index [EI] at shear stress = 1.7 Pa) was reduced in proportion with severity of disease (fatal outcome: EI = 0.182 (SD = 0.048), survivors from severe disease: EI = 0.217 (SD = 0.043), uncomplicated malaria: EI = 0.249 (SD = 0.030), healthy controls: EI = 0.268 (SD = 0.022). All but 2 survivors with severe malaria and rigid erythrocytes received a blood transfusion restoring RCD. Reduced RCD may contribute to impaired microcirculatory flow and a fatal outcome in falciparum malaria. RCD can be improved by blood transfusion. Since severely reduced RCD has a strong predictive value for mortality, blood transfusion possibly improves disease outcome not only through its beneficial effect on anaemia but also on RCD.

Microcirculatory pathways in normal human spleen, demonstrated by scanning electron microscopy of corrosion casts

Confusion regarding microcirculatory pathways in normal human spleen has arisen due to extrapolation from pathological material and from other mammalian spleens, not to mention difficulties in tracing intricate three-dimensional routes from the study of thin sections or cut surfaces of tissue. We examined microcirculatory pathways in normal human spleens freshly obtained from organ transplant donors. A modified corrosion casting procedure was used to obtain an open view of vessels and their connections. Our results demonstrate: 1) "arteriolar-capillary bundles" within lymphatic nodules and extensive branching of arterioles in the marginal zone (MZ); 2) the marginal sinus around lymphatic nodules; 3) the peri-marginal cavernous sinus (PMCS) outside the MZ or immediately adjacent to the nodule itself; the PMCS receives flow via ellipsoid sheaths and MZ, or directly from arterial capillaries, and drains into venous sinuses; 4) fast pathways for flow into venous sinuses via ellipsoid sheaths; 5) arterial capillary terminations in the reticular meshwork of the red pulp or MZ ("open" circulation); direct connections to venous sinuses also occur ("closed" circulation), although rarely; and 6) numerous open-ended venous sinuses in the MZ, allowing a large proportion of the splenic inflow to bypass the red cell filtration sites in the reticular meshwork and at venous sinus walls.

Human hyaline cartilage--biochemical and immunochemical study

Hyaline cartilage from the knee or rib of newborns was divided in neutral salts into a soluble and insoluble part. The insoluble part was treated with collagenase and was separated into 2 peaks by gel chromatography on Sephadex G-200. The 1st peak revealed a low concentration of proteins, no hydroxyproline, and very high levels or uronates. In the 2nd peak, very high values of hydroxyproline and very low values of uronate were found. Thus the 1st peak contained only proteoglycans and no collagen, while the entire collagen was found in the 2nd peak. The individual fractions were inoculated into rabbits to obtain antibodies. Compared to the fraction containing macromolecular proteoglycans, antisera proved remarkably suitable particularly for analysis of human spleen, yet also of other organs. These anti-cartilage antisera visualized primarily spongy structures of pericapillary sheaths and circumferential reticulum of the periarterial lymphatic sheaths, but to a lesser extent also other extracellular structures of the spleen and of other organs.

Outer mantle zone of the follicle in the human spleen

The follicular circumferential connective fibre reticulum, which is a continuation of the circumferencial reticulum (CR) of the periarterial lymphocyte sheaths, was visualized at the periphery of lymphoid follicles in the human spleen by means of anticartilaginous antiserum. If this CR is considered to be the borderline between the follicular and extrafollicular structures, then at the inner aspect of the CR and at the periphery of the fully developed follicle two mantle zones can be distinguished: an inner zone consisting of small lymphocytes, and an outer consisting of medium-sized lymphocytes. Both all groups are B-lymphocytes displaying positive surface IgM. The reticulum is the same in both mantle zones and it is completely different from the reticulum of the marginal zone. In some instances it is so sparse as to appear to be absent completely. The newly delimitated outer mantle zone also has a specific cellular composition differing from the marginal zone. Most importantly, it does not possess that mixture of lymphocytes and other blood cells which is considered to be the defining feature of the marginal zone. The characteristic cellular components of the outer mantle zone are the densely accumulated medium-sized lymphocytes, with other cells interspersed very sporadically.