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Biomedical subjects

W J Koopman

Publications and source records attributed to W J Koopman.

At least 199 records · Page 11Linked to original sources
PubMed1982

Murine Peyer's patch T cell clones. Characterization of antigen-specific helper T cells for immunoglobulin A responses.

We successfully cloned antigen-specific T cells from murine gut-associated lymphoreticular tissue, i.e., Peyer's patches, which are dependent upon T cell growth factor and independent of antigen for continuous growth. These clones exhibit helper activity for IgA responses to sheep erythrocytes (SRBC) and have been designated T helper (Th) A. Two broad categories of Th A clones have been maintained in continuous culture. The first group supports IgM and largely IgA anti-SRBC plaque-forming cell (PFC) responses in both normal and SRBC-primed splenic B cell cultures, whereas the second group supports low IgM, IgG1, and IgG2 and high IgA PFC responses. Subclones derived from single cells maintain the parent helper properties when propagated in culture for long periods (greater than 7 mo). Cloned Th A cells are antigen specific and do not support polyclonal or immune responses to other thymus dependent antigens in normal B cell cultures. Th A cells require full histocompatibility for helper functions because addition of cloned Th A cells to B cell cultures from other H-2 types does not result in IgA responses. Cloned Th A cells are Thy-1.2+ and Lyt-1+ and Lyt-2-, Ig-, and I-A-. Th A cells bear Fc receptors for IgA and do not possess receptors for IgM or IgG isotypes. Thus, T cells that primarily promote IgA isotype responses have been isolated in high frequency from murine PP, an anatomical site of major importance for induction and regulation of the IgA response.

Animals↗
PubMed1982

Seronegative rheumatoid arthritis. A distinct immunogenetic disease?

Measurement of serum rheumatoid factor (RF) by conventional methods in patients with rheumatoid arthritis (RA) has repeatedly identified a subpopulation of patients without detectable RF. Previous investigators have consistently confirmed the association of HLA-DR4 with seropositive RA, but studies of seronegative RA have been limited and contradictory. We studied 140 randomly selected patients from Alabama, all of whom had either classic or definite RA, and we were able to complete HLA typing for 110 of these individuals. Eighty were consistently seropositive (on at least 2 separate occasions) and 30 were consistently seronegative (on at least 3 separate determinations). There was no statistically significant difference between the seronegative RA patients and 123 control subjects in the distribution of DR antigens. In seropositive RA, there was a significant increase in DR4 (P less than 0.001; relative risk = 8.02; attributable risk = 49.2%) and a significant decrease in DR3 (P less than 0.001; relative risk = 0.14) and DR7 (0.01 greater than P greater than 0.001; relative risk = 0.33). The clinical data also distinguished between seropositive RA and seronegative RA; subcutaneous nodules (37.5%) and vasculitis (6.3%) were present only in seropositive RA. DR4 positively did not correlate with any of the clinical variables measured in the seropositive RA group. In contrast, DR4 in the seronegative RA group was associated with more destructive disease. The data suggest that seronegative RA represents a disease entity clinically and immunogenetically distinct from seropositive RA. Moreover, our results indicate that DR4 may be a previously undisclosed marker for disease severity in seronegative RA.

Arthritis, Rheumatoid↗
PubMed1982

Buffer electrofocusing of Interleukin I.

Buffer electrofocusing, utilizing a mixture of low-molecular-weight buffer compounds to establish a stable linear pH gradient covering the range 3.5-6.0 on granulated gel media, has been employed in the purification of Interleukin I with good recovery of biological activity. The difficulties often experienced in the removal of commercial synthetic ampholytes after conventional preparative electrofocusing are avoided in this method.

Ampholyte Mixtures↗
PubMed1982

An enzymatic method for preparation of dissociated murine Peyer's patch cells enriched for macrophages.

Enzyme (Dispase) dissociation of murine Peyer's patches (PP) 3 yields a cell population rich in T and B lymphocytes and containing 5-9% macrophages (MO) as defined by morphology and esterase staining. Cell yields by this method are 3-4 times greater than with conventional mechanical methods and viability of cells always exceeds 95%. The virtual absence of IgA plasma cells (less than 1%) indicates lack of contamination of the cell preparations with intestinal mucosal cells. Enzymatically dissociated PP cells proliferate in response to both T and B cell mitogens. Differences in patterns of mitogen responsiveness of sequentially obtained PP cell fractions are observed suggesting considerable functional heterogeneity of PP cells. Patterns of IgM and IgA synthesis by PP cells in response to the B cell polyclonal activator LPS differ considerably from spleen cells. The development of methodology for preparation of PP cells containing functionally intact T and B cells and enriched for MO should permit analysis of the cellular basis for functional specialization of PP.

Animals↗
PubMed1982

A quantitative assay for IgA rheumatoid factor.

We developed a solid-phase radioimmunoassay capable of detecting nanogram quantities of human IgA rheumatoid factor (RF) in biological fluids. Human IgM RF, IgG RF, IgG, IgA, IgM and whole serum did not significantly interfere with the IgA RF assay. Patients with sero-positive rheumatoid arthritis (RA) had significantly higher concentrations of IgA RF than sero-negative RA patients or healthy adult controls. Concentrations of IgA RF in paired sera and synovial fluids from sero-positive RA patients were comparable. Levels of IgA RF demonstrated a moderately good correlation with levels of IgM RF in sero-positive RA sera (r = 0.673). However, the ratio of IgA RF concentration to IgM RF concentration in sero-positive RA sera varied widely.

Antibody Specificity↗
PubMed1982

In vivo immune response to a T-cell-dependent antigen by cultures of disassociated murine Peyer's patch.

The first line of defense against pathogens that enter the host by the oral route appears to involve the gut-associated lymphoreticular tissue-e.g., Peyer's patches (PP). Although animals can readily be immunized by orally administered antigen that mobilizes the secretory immune system, there is a total lack of local antibody synthesis in the PP and the cellular basis for this deficiency remains a mystery. A lymphoreticular cell population, obtained when murine PP were treated with a neutral protease (Dispase), consisted of accessory cells [macrophages (MPhi)] and T and B lymphocytes. In vitro cultures of these PP cell preparations with the thymic-dependent antigen sheep erythrocytes (SRBC) resulted in good anti-SRBC plaque-forming cell (PFC) responses. The time courses of these responses were identical to those seen with spleen cell cultures. Submitogenic concentrations of concanavalin A (Con A) and optimal doses of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) and lipopolysaccharide (LPS) enhanced in vitro responses of PP cell cultures to SRBC. PP possess fully functional antigen-presenting MPhi because incubation of optimal proportions of splenic T and B cells with purified populations of PP MPhi supported good in vitro immune responses. Murine PP possess all of the necessary elements for an IgA immune response because PP cell cultures derived from mice orally primed with SRBC and immunized with SRBC in vitro gave high IgA anti-SRBC PFC responses. All of the adjuvants tested (LPS, MDP, and Con A) enhanced IgA responses in PP cell cultures from orally primed mice; however, Con A induced the greatest enhancement. These results demonstrate that murine PP possess MPhi capable of accessory cell functions for in vitro immune responses and that oral priming with antigen induces the precursor T- and B-cell populations necessary for IgA responses, that are potentiated by adjuvants, in PP cell cultures. Thus, murine PP possess the lymphoreticular cells required for antibody responses; however, the tissue architecture likely prevents local responses in vivo. The finding that enzymatically dissociated PP contain all of the necessary cellular components for antibody synthesis, whereas the in vivo tissue architecture prevents the complex interactions necessary for this response, suggests that the initial inductive events take place in situ, and additional cell interactions are required for final differentiation of IgA-synthesizing plasma cells to occur at distant mucosal sites.

Animals↗
PubMed1981

Interleukin 1: production by P388D1 cells attached to microcarrier beads.

The murine macrophage-derived cell line P388D1 is commonly used for the production of Interleukin 1 (IL1) and other macrophage products. In order to circumvent the tendency of this cell line to undergo selection for a non-adherent subpopulation of cells which does not produce IL1, we have grown P388D1 cells attached to microcarrier beads. IL1 produced by these cells is indistinguishable from that elaborated by cells grown in monolayer or suspension culture. Moreover, several volumes of conditioned medium can be produced from one batch of cells suitable for the large-scale purification of this mediator.

Animals↗
PubMed1980

Production of predominantly polymeric IgA by human peripheral blood lymphocytes stimulated in vitro with mitogens.

Human peripheral blood lymphocytes (PBL) were cultured for various time periods (up to 8 d) in the presence of pokeweed mitogen (PWM), lipopolysaccharide, or Epstein-Barr virus. Cell-free supernates were fractionated on a standardized ultrogel AcA 22 column and the proportion of polymeric and monomeric IgA was determined by radioimmunoassay. The results demonstrate that PBL stimulated with these mitogens produce IgM and IgG with molecular characteristics identical to those found in serum, but that the IgA produced is predominantly of the polymeric type. To prove that this IgA represented disulfide bond-linked polymers rather than aggregated monomers, we have demonstrated that the high molecular weight IgA (a) maintains its polymeric form upon treatment with acidic buffers, (b) contains J chain, a glycoprotein associated only with polymeric immunoglobulins, and (c) dissociates to the monomeric form upon reduction of disulfide bonds. After 1 wk in culture, approximately 60% of the PWM-stimulated cells that contained IgA were positive for IgA2, whereas 40% were IgA1 positive as determined by immunofluorescence. Therefore, peripheral blood contains a population of lymphocytes with the potential to display, after appropriate stimulation and differentiation, characteristics similar to IgA cells found in external secretory tissues. The demonstration of the presence of such cells in the peripheral circulation suggests that these cells are precursors of IgA-producing plasma cells with the potential to populate mucosal tissues.

Humans↗
PubMed1980

A sensitive radioimmunoassay for quantitation of IgM rheumatoid factor.

A solid-phase radioimmunoassay capable of detecting nanogram quantities of human IgM rheumatoid factor (RF) in biologic fluids has been developed. Binding curves for monoclonal IgM RF and polyclonal IgM rheumatoid factors were similar under the conditions utilized for the assay. Human IgG did not interfere with the detection of IgM RF by this method. Small quantities (less than or equal to 0.2%) of nonspecific binding by nonRF IgM to the human IgG coated tubes utilized in the assay were corrected for by assaying samples in parallel bovine serum albumin coated control tubes. As expected, patients with seropositive rheumatoid arthritis (RA) had significantly higher concentrations of IgM RF than seronegative RA patients (mean +/- 1 SD = 652 +/- 553 microgram/ml versus 11.3 +/- 13.3 microgram/ml, P less than 0.001). In contrast, all normal control sera assayed to date contained less than 0.1 microgram/ml of IgM RF. The capacity of the assay to detect nanogram quantities of IgM RF should permit investigation of the cellular mechanisms underlying RF production.

Arthritis, Rheumatoid↗
PubMed1980

Enhanced in vitro synthesis of IgM rheumatoid factor in rheumatoid arthritis.

Peripheral blood mononuclear leukocytes (MNL) from 42 patients with classic/definite seropositive rheumatoid arthritis (RA) and 24 healthy adult controls were tested for their capacity to produce IgM rheumatoid factor (RF) in vitro in the presence and absence of pokeweed mitogen (PWM). In no instance was spontaneous elaboration of IgM RF from control MNL observed. In contrast, MNL from 16 of the 42 RA patients spontaneously synthesized IgM RF (22 +/- 43 ng/culture) which constituted a substantial fraction of the total IgM in these culture fluids (48 +/- 26%). Pokeweed mitogen induced detectable quantities of IgM RF in MNL culture supernatants from 10 of 24 controls (12 +/- 11 ng/culture) and 33 of 42 RA patients (60 +/- 82 ng/culture, P = 0.008). IgM RF constituted a significantly higher proportion of the total IgM in RA MNL supernatants than in control supernatants (11 +/- 11% versus 1.01 +/- 1.03%; P = 0.013). IgM RF production (spontaneous and PWM-induced) was dependent upon de novo protein synthesis. The results indicate that B cells programmed to produce IgM RF are present in both normal and RA B cell repertoires, but are preferentially expressed in RA.

Animals↗
PubMed1980

In vitro synthesis of IgM rheumatoid factor by lymphocytes from healthy adults.

Peripheral blood mononuclear leukocytes (MNL) from 22 healthy adults were tested for their capacity to produce IgM rheumatoid factor (RF) in vitro in the presence and absence of pokeweed mitogen (PWM). In no instance was spontaneous elaboration of IgM RF observed. However, stimulation of MNL with PWM resulted in the induction of IgM RF synthesis in 10 out of 22 individuals. The IgM RF in these culture fluids constituted only a small fraction of the total IgM (mean +/- 1 S.D. = 1.01 +/- 1.08%). The lack of correlation of IgM RF with total IgM in these culture fluids argued against nonspecific absorption of non-RF IgM on the IgG substrate utilized in the assay. Furthermore, fraction of supernatants containing IgM RF on Sephadex G-200 indicated the material to co-elute with polymeric IgM and to preferentially bind to Fc coated tubes as opposed to Fab or BSA-coated assay tubes. IgM RF production induced by PWM was dependent upon de novo protein synthesis and exhibited T cell dependence. The data indicate that B cells capable of synthesizing RF commonly occur in normal individuals but are not ordinarily activated.

Animals↗