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Biomedical subjects

J C Bensa

Publications and source records attributed to J C Bensa.

At least 55 records · Page 3Linked to original sources
PubMed1984

Role of C3 in the control of monocyte C2 production.

Serum-treated antigen-antibody complexes (IC) and DTSP-polymerized C3b and C3c inhibited the production of the second complement component (C2) by monocytes in culture, whereas monomeric C3, C3b, C3bi, C3c or C3d had no effect. The degree of inhibition of dithiobissuccinimidyl propionate (DTSP)-polymerized C3 was proportional to the degree of polymerization, dimer exhibiting less inhibitory activity than larger molecular weight polymers. The inhibitory effect of serum-treated IC and DTSP-polymerized C3b was abrogated by their pretreatment with Fab fragments of anti-C3, or pretreatment of monocytes with Fab fragments of antiserum to the C3b receptor (CR1). We have concluded that the inhibition of C2 production produced by serum-treated IC is due to bound C3b or C3bi, and is mediated by CR1. Furthermore cross linking of receptors is required for this effect; two or more than two receptors must be cross-linked for a significant effect to be observed.

Antigen-Antibody Complex↗
PubMed1983

[Role of immunoglobulins in the activation of complement].

Depending on their class and sub-class, immunoglobulins may activate the complement by the classical pathway or by the alternative pathway. This activating property depends on how immunoglobulins are associated. Activation by the classical pathway implies binding to, and activation of C1. Binding is essentially an ion type interaction between C1q and--in the case of human IgG's for instance--the C gamma 2 domain. It has recently been investigated in depth by various techniques, such as inhibition of the C1q--IgG interaction by chemical compounds or by peptides isolated from C gamma 2. Activation of C1 seems to involve some elements of C gamma 3. In addition to initiating the classical pathway, immunoglobulins may act as acceptors of the classical C3-convertase (C4b C2a); a structure accepting the newly formed C4b is present in the Fab portion of IgG. It would appear that optimal functioning of the complement system is achieved when the C1 activating site and the C3-convertase forming site are close together on the IgG molecule, since the newly born peptidic fragments have a very short life. Immunoglobulins may activate the alternative pathway via their Fab portion. This property is directly related to the ability of Ig's to accept nascent C3b, which probably includes that of accepting nascent C4b as described above. In the alternative pathway C3-convertase may form when structural conditions around IgG-bound C3b encourage binding of B to C3b rather than the intervention of I and H factors which degrade C3b. The Ig-C3b interaction responsible for activation of the alternative pathway may also be directly involved in solubilization of immune complexes during activation of complement.

Animals↗
PubMed1983

Biosynthesis in vitro of complement subcomponents C1q, C1s and C1 inhibitor by resting and stimulated human monocytes.

The capacity of cultured human monocytes to synthesize and to secrete the subcomponents of C1 and C1 inhibitor was examined. Non-stimulated monocytes secreted C1q and C1s from day 5 of culture. C1s reached a plateau immediately at its maximum level, whereas C1q secretion increased progressively until the end of the second week. Between day 12 and day 25, C1q secretion remained nearly constant (1-15 fmol/day per microgram of DNA, depending on the donor), whereas C1s secretion decreased and even in some cases stopped. C1r and C1 inhibitor were not secreted in detectable amounts by these resting cells. Stimulation of monocytes by yeasts, immunoglobulin G-opsonized sheep red blood cells or latex beads did not modify consistently C1q and C1s secretion. Activation by conditioned media from mitogen-, antigen- or allogeneic-stimulated lymphocyte cultures increased C1q production from 2 to 7 times and re-activated C1s secretion. Under the same conditions of activation, C1 inhibitor was secreted (up to 300 fmol/day per microgram of DNA) and C1r became detectable in culture supernatants. Isolated human monocytes are thus able to synthesize the whole C1 subcomponents; C1, if assembled, could be protected from non-immunological activation by locally produced C1 inhibitor. Activated monocytes appear to be a good tool for studying the assembly of C1 subcomponents and the role of C1 inhibitor in this process.

Cells, Cultured↗
PubMed1983

[Cellular immunity in idiopathic nephrotic syndrome with minimal glomerular lesions and focal and segmental hyalinosis in children].

Cellular immunity was studied in 31 children presenting with idiopathic nephrotic syndrome (INS), of which 23 with minimal supposed or proven glomerular changes (MGC) and 8 with focal and segmental hyalinosis (FSH). In vivo, a clear hyporeactivity to the delayed hypersensitivity tests and decreased blood T lymphocytes, with a great dispersion of the values were found. Furthermore, such patients' sera display a factor inhibiting the proliferative response of the lymphocytes of patients and of control subjects, to non specific mitogens (PHA), both during exacerbation and remission periods. The hypotheses of an abnormality of cellular immunity and of the existence of an inhibitory factor in the serum of INS with MGC and FSH are discussed.

Adolescent↗
PubMed1982

Non-Hodgkin's malignant lymphomas: a cytologic classification based on statistical analysis and correlated with prognosis.

On the basis of cytologic studies of 144 patients with non-Hodgkin's malignant lymphomas (NHML), a cytologic classification was established that was composed of three groups (1, 2 and 3) containing nine classes (1A, 1B, 1C; 2A, 2B, 2C; 3A, 3B, 3C). Statistical analyses were carried out using 52 well-defined elementary cytologic characteristics. All the results given by the data-gathering procedures (hierarchical and dynamic clustering methods), by the descriptive analyses (multifactorial and canonical analysis) and by the stepwise discriminant analysis were in agreement with the proposed cytologic classification system. The most discriminating cytologic characteristics of the classes were the cell size, the nuclear-cytoplasmic ratio, the degree of cytoplasmic basophilia, the homogeneity of the cytoplasm and the number of mitoses. The use of these properties renders this classification system reproducible and applicable to clinical practice. A comparison was made between the cytologic classes and the NHML patients as grouped according to their clinical courses. Of the patients in classes 2A, 2B and and 2C, 94% showed acute leukemic characteristics. Of those contained in classes 3A, 3B and 3C, 78% showed poor prognosis or metastatic patterns. Of those contained in classes 1A, 1B and 1C, 76% showed a good prognosis pattern.

Adolescent↗
PubMed1982

The short effect of pelvic radiotherapy of gynecological cancers on humoral and cell mediated immunity.

An analysis of short effect of pelvic irradiation on cellular and humoral immunity was made in 24 patients treated by irradiation alone or a combination of surgery and irradiation for uterine carcinoma, at 2, 6, 12 months after loco-regional therapy. Twelve months later there is a decrease of T lymphocytes (P = 0.01), whereas the B lymphocytes count is normal; the percentage of T and B lymphocytes remains stable, but the lymphocyte response to PHA after 3 days is reduced (p = 0.03). A significant decrease of immunoglobulins G, A and M is observed.

Adult↗
PubMed1980

[Agranulocytosis in the course of infectious mononucleosis. Demonstration of leukoagglutinins (author's transl)].

A case of agranulocytosis, quickly and spontaneously reversible, occurring in the fourth week of infectious mononucleosis in a 7-year old girl, is reported. The interest of the case lies in the importance of the symptomatology (jaundice, eruption, fever for 40 days), the serological detection of the role of the Epstein-Barr virus and, in particular, in the presence of leukoagglutinins judged to be responsible for the agranulocytosis.

Agglutinins↗
PubMed1979

[Lymphopenia and variations in T and B lymphocytes appearing immediately after irradiation (author's transl)].

Immunity tests were conducted in 21 patients with cancer, before and two months after irradiation. T and B lymphocyte counts were normal before irradiation when compared to a control group. Lymphopenia was present after irradiation affecting mainly the T lymphocytes (P = 0.005), whereas changes in B lymphocytes were not significant. These results suggest that irradiation has an immunosuppressive effect which should be studied in greater detail to establish possible therapeutic applications.

Adult↗
PubMed1977

Quantitative study of T and B lymphocytes in Hodgkin's disease.

Peripheral blood lymphocytes forming E rosettes in the presence of sheep red blood cells and those bearing surface immunoglobulins (SIg) have been studied quantitatively as an evaluation of T and B lymphocytes in Hodgkin's disease. 62 patients were investigated, 21 of whom before any treatment. It appears that the lymphocytes forming E rosettes are significantly lower in percentage in 86% of the patients and in absolute count in 65%. SIg bearing lymphocytes are elevated in percentile in 61% of the cases, but the absolute count is normal in 50% of the patients and elevated in 30% only. At diagnosis the T/B lymphocytes equilibrium is modified in 13 among 21 patients but, after the initial treatment of the disease, the ratio is modified in 90% of the patients in complete remission and remains unchanged for years even in the absence of relapse or immnunosuppressive treatment. It is suggested that SIg + lymphocytes from the peripheral blood are actually B lymphocytes and not anti-T-antibody coated T lymphocytes or antigen-antibody lacking of membrane markers, which are numerous in one third of the investigated patients, might be T lymphocytes with qualitative abnormality.

Adult↗
PubMed1977

A human immunoglobulin in myeloma protein with anti-gastric parietal cell autoantigen activity.

A previously characterised IgA Kappa myeloma protein was isolated and purified. The (Fab) alpha fragments of this immunoglobulin were obtained. The IgA and Fab fragments reacted in vitro with gastric parietal cells (GPC) using animal gastric sections and with smooth cytoplasmic membranes obtained from rabbit fundus (gastric) mucosa. This was seen macroscopically and by light and electron microscopy. Evidence is thus provided which supports the concept that this homogeneous immunoglobulin is a typical monoclonal autoantibody.

Autoantibodies↗