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The Greek term stroma literally means in translation mattress, covering or bed. In the medical context this describes the connective tissue framework of an organ which is composed of the stromal cells and the extracellular matrix components which are produced by these cells. According to the original definition stromal cells have a non-hematopoietic origin and adherently grow in cell culture. Nowadays the term is used to cover a heterogeneous group of connective tissue cells of mesenchymal origin which includes fibroblasts, reticular stromal cells and endothelial cells as well as tissue-specific connective tissue cells, such as osteoblasts and adipocytes. Because the stromal cells in the various tissues are very different with respect to morphology and functional characteristics, the manifold aspects of the individual stromal cell populations are now just beginning to be understood. This article presents a summary of new knowledge on the various functions of stromal cells in the immune response.

Local morphological reaction patterns on breast implants can be of high significance as possible starting point for controversely discussed systemic immune response triggered by silicon or silicone. Therefore, the collagenous capsules of 149 explanted mammoplasty prostheses were examined macroscopically, under a scanning electron microscope and light-microscopically using antibodies to the macrophage antigen CD68, vimentin, muscle actin, and the proliferation antigen MIB1, and were then correlated with anamnestic data (implanted type of prosthesis, indication for im- or explantation). According to our examinations, the in-vivo durability of the prostheses' shells is considerably decreasing with the expansion of their surfaces. Regardless of the type of the prostheses' surface regularly a chronic-proliferating inflammation pattern could be identified in the periprosthetic capsulectomy specimens starting with a synovial metaplasia of proliferating CD-68-negative and vimentin-positive mesenchymal cells in the area surrounding the implants and ending by its transformation into a stage of dense hyaline collagenous fibrous tissue after an advanced implantation period (> 2 years). By this, the texturing of the prosthesis surface modifies only the course, but not the quality of the chronically fibrosing inflammation. Bleeding of prosthesis as well as the incorporation of the polyurethane-foam coating of different prosthesis types into the periprosthetic breast capsule lead to a significant lymphoplasmacytic infiltration, partly with participation of local vessels as defined in a "silicone vasculitis". Morphological signs of an at least local immune response are detectable in 8.3% of the examined fibrotic capsules even without a morphologically identifiable foreign-body embedding. They can be possibly referred to- as well as the complete absence of hyaline collagenous fibrous tissue in 30% of the cases-a yet not causally clarified, inter-individually different susceptibility of the implant bearers. Only the systematic registration of the above-mentioned morphological reaction patterns in a "prosthesis-passport" together with the additional clinical observation of the patients can ensure in future the realistic estimation of potential health risks caused by silicone breast implants.

Sclerodermas may occur in two basic forms: localized sleroderma (LSc) and systemic scleroderma (SSc). Pseudoscleroderma as well as overlap syndromes have to be differentiated from these two variants. From the clinical point of view, localized scleroderma can be subdivided into type I = plaque-like LSc (= morphea), type II = linear LSc, and type III = deep LSc. According to the degree of the cutaneous involvement, systemic scleroderma can likewise be classified into type I = sclerodactylia, type II = acrosclerosis, and type III = scleroderma with primary involvement of the trunk (diffuse scleroderma). In LSc, we never find systemic involvement; SSc, in contrast, is almost always associated with Raynaud's phenomenon, changes of the esophagus, as well as an increased titer of antinuclear antibodies (Hep-2 cell test). Only 23% of our patients with LSc showed elevated ANA titers. We present and discuss data of 56 patients with LSc and 52 patients with SSc. Evidence in the literature as well as our own findings suggest that the pathogenesis of LSc is different from that of SSc. The influence of various mediators and cytokines on the collagen metabolism might be regarded as a theoretical approach in order to develop new therapeutic regimens. This is even more important since there is still no efficient mode of treatment for neither localized nor systemic scleroderma.

The fluorescent antibody technique is nowadays mainly a technique, which is routinely carried out in all clinical-immunological laboratories. The main fields of application in clinical immunology are the determination of autoantibodies (e.g. ANA, AMA, smooth muscle antibodies, parietal cell antibodies), detection of B-lymphocytes as well as bacterial antigens (e.g. Treponema pallidum). Furthermore the demonstration of deposits of immune complexes in tissues (e.g. glomerulonephritis, periarteriitis nodosa). The presented paper shows the different fields of application of the fluorescent antibody technique. It is pointed out that the FAT could be only one out of the variety of methods in clinical-immunological investigations.

In a random sample of so-called healthy blood donors under and over 60 years of age (n=196 of 10,593 donations by about 4254 donors) the frequency of antibodies (antibodies against smooth muscles, mitochondria, microsomes, brush border of proximal rat renal tubuli, connective tissue, and parietal cells) detectable by immuno-fluorescence was determined and compared with the incidence thereof in various groups of diseases. In general, two frequency peaks (up to 30 and over 50 years of age) were observed; however, statistical evidence was obtained for the second peak only (with p less than 0.001). In "healthy" blood donors past 60 there was observed a significantly higher frequency of occurrence of antibodies against parietal cells (p less than 0.001) and against connective tissue (p less than 0.01). An attempt has been made to classify antibodies into four groups depending upon age disease, with due consideration being given to the different clinical valency of antibodies. Different frequencies of occurrence of numerous antibodies are believed to be due not only to immune system aging, but especially to the not-yet elucidated disturbance of regulation of autotolerance by alteration of immune cells, which is subject to endogenous (e.g., genetic) and exogenous (e.g. viral) factors that are dependent on age rather than aging.

Unfixed cryostat sections of an organ block comprising the liver, stomach, and kidney of rats as well as the kidney of mice were used as antigenic substrate for detecting antibodies against connective tissues by indirect immunofluorescence. There were found more than 14 different fluorescent patterns. Two types could be distinguished easily: The "type 1" shows a clear fluorescence of fine perivascular fibres and a faint fluorescence of vascular endothelium in the liver and in the kidney. The sinusoids are negative. The "type 2" is characterized by a bright and broad fluorescence of the sinusoids and of the portal tract without perivascular staining of the liver. On the sections of the kidney a fluorescence of vascular endothelium, of the tubular basement membrane or of the peritubular connective tissue fibrils is typical.

Using monoclonal antibodies directed towards distinct cell surface antigens of the monocyte/macrophage lineage, we tried to disclose diagnostically relevant differences in the distribution pattern of monocytes and macrophages in cryostate sectioned synovial tissue samples from patients with rheumatoid arthritis and osteoarthrosis, psoriatic arthritis (n = 1) and a healthy control subject. As compared to osteoarthrosis, we found that in rheumatoid arthritis, accessory cells of the T- and B-cell immune response are pronounced in the basis areas of the superficial cell layers, indicating an active inflammatory process of immunological origin. Applying monoclonal antibodies specific for monocytes and immature macrophages of connective tissue, we confirmed the finding of an enhanced migration of those cells from the peripheral blood stream into the inflamed synovial tissue. Despite those findings, we were not able to demonstrate significant immuno-morphological differences between tissue from patients with rheumatoid arthritis and osteoarthrosis.

The results reported in this paper clearly indicate the release of osteal antigens of articular connective tissue in response to inflammatory alterations and injuries to the region immediately adjacent to an articulation. Further studies will have to be performed in an effort to find out whether these antigens are of pathological importance and if there is a relationship between the liberation of antigens and the intensity of inflammatory alterations or if the different and often difficult-to-interpret results of the determination of antibodies in the sera of patients with rheumatoid arthritis can be more easily explained by a simultaneous antigen analysis of the corresponding sera.

Unlabelled: In neonatally thymectomized mice, the intermediate cortical zones of the lymph nodes as well as the central portions of the spleen follicles (=thymus dependent areas, TDA) are depleted of lymphocytes within a few weeks (Parrott et al., 1966). The TDA's in the lymphatic tissues of mice homozygous for the gene "nude" (nu/nu) contain also a very small number of lymphocytes. Since only a few developmental stages of the lymphatic tissues in nude mice have been studied, an investigation of the postnatal differentiation of their lymph nodes and spleen seemed worthwhile., Materials and Methods: The mice (BALB/c) were maintained under specific pathogen-free (spf) conditions. Heterozygous (nu/ plus) females were mated with homozygous (nu/nu) males in order to obtain the homo- and heterozygous offsprings used in this study. Two nu/nu and two nu/ plus female mice were sacrificed at the following postnatal stages: day 1, 7, 14, 21, 35, 42, 49, 63 and 84, respectively. Newborn and 7 day old mice were fixed in toto in Bouin's solution and embedded in paraffin. From the other animals, spleen and mesenteric lymph nodes were removed and processed in an identical manner. Serial sections were cut at 5 mum and stained with hematoxylin and eosin., Results: The mesenteric lymph nodes of the nu/ plus mice studied were indistinguishable from those of other mouse strains. In the nu/nu mouse, outer cortex and medulla of the mesenteric lymph nodes were found to develop as in normal (nu/ plus) animals, while the intermediate and deep cortex underwent characteristic changes...