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Biomedical subjects

G J Lafeber

Publications and source records attributed to G J Lafeber.

25 records · Page 2Linked to original sources
PubMed1976

Morphological differences in the interactions between human mononuclear cells and coated or uncoated sheep red blood cells: a freeze-etch study of different types of rosettes.

Enriched preparations of E, EA and EAC rosettes formed by human peripheral blood mononuclear cells were freeze-etched and examined electron-microscopically. In E rosettes only lymphocyte were involved, whereas in EA and EAC rosettes lymphocytes and mononuclear phagocytes participated as rosette-forming cell. In EA and EAC rosettes, cytoplasmic extensions of the rosette forming cell were seen to penetrate the sheep red blood cell, whereas E rosettes showed a broad zone of adherence without penetration. None of the three types of rosettes showed an interspace between the membranes. Unlike E rosettes, EA and EAC rosettes showed polarity in the adherence of sheep red blood cells. These observations made by freeze-etch electron microscopy indicate distinct morphological differences between rosettes formed with coated or uncoated erythrocytes.

Animals↗
PubMed1975

Immunoglobulin phagocytosis by granulocytes from sera and synovial fluids in various rheumatoid and nonrheumatoid diseases.

(1) The phagocytosis of human IgG, IgM, and C3 by granulocytes from various rheumatoid and nonrheumatoid sera and synovial fluids (SF) was investigated by direct examination of the patient's leucocytes and indirect testing by incubation of normal donor leucocytes with various sera and SF. (2) In rheumatoid arthritis (RA) phagocytosis of IgM, IgG, and C3 was common from sera and SF. There was a strong correlation of IgM and C3 phagocytosis with the occurence of rheumatoid factor. The phagocytosed IgM is probably rheumatoid factor. In SF both the direct and indirect test method yielded equally positive results; in serum the direct test was negative throughout. (3) In systemic lupus erythematosus there was phagocytosis of IgG, IgM and C3 from serum (indirect test), IgM not being correlated with the latex-fixation test and probably of antinuclear antibody nature. Phagocytosis decreased after treatment of the disease. Sera from many other rheumatic disease frequently gave weak IgG phagocytosis, but rarely did IgM or C3. (4) IgG, and sometimes C3, was frequently taken up from IgG myeloma sera (indirect test). IgM and IgG were taken up from Waldenström's macroglobulinaemia sera, independent of IgM concentration. It is possible that an aggregation tendancy of particular paraproteins determines Ig uptake from these sera. (5) IgG was taken up from half of the studied sera of infectious diseases in the indirect test, including two cases with Hodgkin's disease as well. Three sera from patients with untreated trypanosomiasis were positive for IgG as well as for IgM. (6) Normal healthy control sera remained negative, even after prolonged preservation or frequent freezing and thawing: only among very old sera were a few positive observations recorded. Immunoglobulin phagocytosis appears to be a common phenomenon in a number of conditions. It seems probable that soluble immune complexes, or in other cases nonimmune aggregates, may cause phagocytosis.

Antibodies, Antinuclear↗
PubMed1975

Lymphocytes in rheumatoid and nonrheumatoid synovial fluids. Nonspecificity of high T-cell and low B-cell percentages.

Lymphocytes were studied in paired peripheral blood and synovial fluid samples from patients with various forms of arthritis, including rheumatoid arthritis (group I) and other polyarthritides of unknown origin (group II), as well as arthritides generally considered not to be immunologically mediated, such as crystal synovitis, traumatic arthritis, osteoarthrosis, and pigmented villonodular synovitis (group III). In all 3 groups the percentages of T lymphocytes were significantly higher in synovial fluids than in the peripheral blood, whereas those of the synovial fluid B lymphocytes were consistently very low and occasionally nil. Absolute numbers of synovial fluid lymphocytes were significantly higher in groups I and II as compared with group III, and in the peripheral blood absolute numbers of lymphocytes in groups I and II were significantly lower than in controls. No correlation was found between absolute numbers of lymphocytes and complement activity in the synovial fluid. The characteristic pattern of high T-cell and very low B-cell percentages in synovial fluids is a general feature of inflammatory exudates and cannot be considered an expression of cell-mediated immunity in itself.

Arthritis↗
PubMedDate not supplied

T lymphocyte subpopulations in rheumatoid arthritis.

The number of various lymphocyte subpopulations in the peripheral blood of 28 patients with definite rheumatoid arthritis (RA) were studied. The results were correlated with the disease activity, as assessed by the Ritchie index, erythrocyte sedimentation rate and clinical impression. Patients with active RA showed decreased numbers of T mu lymphocytes, strongly increased numbers of Tnull lymphocytes and slightly increased percentages of Fc gamma lymphocytes as compared to 22 healthy donors. Patients with inactive RA had similar, less striking, but significant changes in T mu and Tnull lymphocytes, but in contrast to patients with active RA had Increased numbers of T gamma lymphocytes. The imbalances in T mu and Tnull cells in patients with RA might be explained by endogenous T mu cell activation, resulting in increased numbers of Tnull cells.

Adult↗
PubMedDate not supplied

In situ localization of lymphocyte subsets in synovial membranes of patients with rheumatoid arthritis with monoclonal antibodies.

Immunological analysis of the mononuclear infiltrates in 12 rheumatoid synovial membranes was performed by means of modified peroxidase antiperoxidase technique using a panel of monoclonal antibodies, directed against T cell differentiation antigens and HLA-DR (Ia-like) antigens. Helper/inducer T lymphocytes (OKT4 +, Leu3a+) were found in large numbers in nodular lymphoplasmocellular infiltrates, whereas the number of cytotoxic/suppressor T lymphocytes (OKT8 +m Leu2a+) was very low, resulting in a high T4/T8 or Leu3a/Leu2a ratio (6á14:1). In diffusely localized lymphoplasmocellular infiltrates this ratio was only slightly increased as compared with the peripheral blood of patients with rheumatoid arthritis (2á4:1). Moreover, most of these T lymphocytes appeared to have Ia-like antigens and seemed to have contact with HLA-DR+, sometimes weakly OKT6+ dendritic nonlymphoid cells. The results showed a constant basic localization pattern of T lymphocyte subsets and suggest that interactions between dendritic nonlymphoid cells, T lymphocyte subsets and B lymphocytes determine the ultimate architecture of the inflammatory infiltrates in the rheumatoid synovial membrane.

Antibodies, Monoclonal↗