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Biomedical subjects

M Ferrarini

Publications and source records attributed to M Ferrarini.

At least 163 records · Page 9Linked to original sources
PubMed1977

Receptors for IgM on certain human B lymphocytes.

A receptor for IgM was demonstrated on the surface of human B lymphocytes by using a rosette technique with ox erythrocytes coated with rabbit IgM antibody (EAM). Lymphocytes forming rosettes with EAM did not bind sheep red cells, had membrane Ia-like antigens and, in some instances, surface immunoglobulin. The specificity of EAM rosettes was confirmed by inhibition experiments with purified human Ig. IgM but not IgG molecules inhibited the rosette reaction. In addition, inhibition of EAM rosettes with IgM fragments showed that the receptor has affinity for a part of the molecule located in the Fc portion. By analogy with the receptors previously found on certain human T cells, receptors for IgM were not detected on freshly isolated B cells, but were expressed after overnight culture in IgM-free media. Studies on different human lymphoid tissues showed that IgM receptors are expressed on a limited percentage of both circulating and noncirculating B cells. In addition to normal B cells, the malignant B cells of a majority of cases of chronic lymphocytic leukemia expressed the receptors for IgM.

Animals↗
PubMed1977

Increased serum IgD concentrations in patients with Hodgkin's disease.

Serum IgD concentrations have been determined in twenty-one patients with Hodgkin's disease, in eight patients with non-Hodgkin's lymphomas and in twenty-eight normal (control) individuals by both a solidphase radio-immuno-assay and radial-immunodiffusion. Fourteen of the Hodgkin's patients displayed three to forty-five-fold increased serum IgD levels as compared to control individuals, while in the remaining seven patients IgD concentrations were practically normal. Patients with non-Hodgkin's lymphomas had decreased IgD concentrations.

Hodgkin Disease↗
PubMed1976

Membrane Ig on MPC11 myeloma cells: correlation between the expression of membrane Ig, a receptor for Ig and the process of secretion.

The expression of membrane immunoglobulin (mIg) was examined in three cloned MPC11-derived mouse myeloma cell lines. Membrane immunofluorescence studies demonstrated that IgG2b producer cells (P1) had complete IgG molecules, L-chain producer (L1) had only L-chain determinants and nonproducer (NP2) did not have any Ig determinants on the cell surface. An Ig receptor, with characteristics different from B lymphocyte Fc receptor, has been found to be present on secreting cells (P1 or L1), but not on the NP2 cell variant. The data reported in the present paper indicate that the expression of mIg and of the Ig receptor molecule is clearly correlated with the process of secretion. In the light of previous data reported on Ig secretion, a model is proposed which correlates the process of secretion with the expression not only of mIg, but also of the receptor for Ig.

Binding Sites, Antibody↗
PubMed1976

Membrane Ig on human lymphocytes: rate of turnover of IgD and IgM on the surface of human tonsil cells.

The turnover of IgM and IgD molecules present on the membrane of human tonsil cells has been studied using immunofluorescence and peroxidase-catalyzed membrane radioiodination. With the first of the two techniques cells were treated with pronase to remove membrane immunoglobulin (mIg), placed in culture and stained at intervals to check the reappearance of membrane IgD and IgM on the cell membrane. These experiments showed that membrane IgD (in contrast to membrane IgM) are extremely susceptible to proteolysis. Furthermore, cells treated with a concentration of pronase found to be optimal to remove membrane IgM failed to re-express membrane IgD in vitro. The large majority of tonsil lymphocytes has both membrane IgM and IgD. Due to the different behavior of reappearance of the two membrane molecules after treatment with pronase, it was not possible to obtain the simultaneous re-expression of membrane IgM and IgD by the cells "stripped" with pronase. However, the two molecules were re-expressed in vitro by the cells treated with different pronase concentrations with a similar timing, i.e. 50% or more of the cells re-expressed membrane IgD and IgM after 8 h in culture. 131I-radioiodinated membrane IgD and IgM were also released from the cell surface with a similar timing, the half-life of permanence on the cell membrane being about 4 h for both molecules. These findings thus indicate that IgM and IgD molecules have a similar turnover and that a cell is capable of placing two different Ig molecules at a time on its surface.

Cells, Cultured↗
PubMed1976

Human T cell receptor for IgM: specificity for the pentameric Fc fragment.

The specificity of the IgM receptor expressed by human T cells cultured in IgM-free media has been investigated. IgM receptors have been detected using a rosette system with ox erythrocytes coated with rabbit antibody (EA(IgM)), and the inhibitory capacity of different IgM fragments in the rosette system has been tested. It was found that F(c)5mu but not F(ab')2mu, nor monomeric IgM (8 S IgM) inhibited EA (IgM) rosette-forming cells. This indicates that the receptor present on the surface of T cells has affinity for a structure located in the Fc portion of the pentameric IgM.

Binding Sites↗
PubMed1976

A study of immunoglobulin classes present on the membrane and in the cytoplasm of human tonsil plasma cells.

The problem of whether immunoglobulin (Ig)-containing plasma cells expressed membrane Ig has been investigated using cells from human tonsils. In tonsils, IgG-containing cells are predominant, but a certain number of IgM, IgA and IgD-containing cells are also present. By using a double staining immunofluorescent technique for the simultaneous detection of membrane and intracytoplasmic Ig, it has been possible to ascertain that the large majority of IgA, IgM and IgD-containing cells had membrane immunoglobulin (mIg) of a class coincident with that of intracytoplasmic Ig. In addition a noticeable proportion of IgM-containing cells expressed membrane IgD, thus indicating that a certain number of these cells bore both membrane IgM and IgD. About 60% of IgG-containing cells had membrane IgG, while the remaining cells did not express mIg. Furthermore the surface staining of these cells was generally fainter than that of the cells containing other Ig classes. Experiments on the surface light chain type expressed by the single Ig-containing cells (IgCC) as compared to that found in the cytoplasm have shown that in the large majority of IgCC the light chain type of mIg coincided with that of intracytoplasmic Ig. Discordant light chain types of membrane and cytoplasmic Ig were found on about 12% of IgCC only. These values can be taken as a measure of how many IgCC had passively acquired mIg.

Cytoplasm↗
PubMed1976

Subpopulations of human T cells identified by receptors for immunoglobulins and mitogen responsiveness.

Human T lymphocytes in peripheral blood have been shown to have receptors for IgG (Tgamma) or IgM (Tmu). Cultured Tgamma cells do not express receptors for IgM and purified Tmu cells do not have receptors for IgG, thus they appear to be distinct T cell populations. Although the two subpopulations show similar response patterns to concanavalin A, Tmu and Tgamma cells exhibit different dose-response curves to phytohemagglutinin. The normal response pattern to phytohemagglutinin requires a mixture of T cell subpopulations suggesting that synergistic interactions may occur.

Binding Sites, Antibody↗
PubMed1975

Comparative study of membrane and intracytoplasmic immunoglobulin classes in human lymphoid cells.

Immunofluorescent and "in vitro" biosynthetic techniques have been used to study the connections between the maturation process of human lymphocytes that leads to the appearance of actively secreting cells and a possible switchover from IgD to IgM production, both in homogeneous CLL cell populations and in heterogeneous cell suspensions from tonsils. The results obtained are compatible with the hypothesis that the switchover from IgD to IgM productions can be a clonal maturation phenomenon.

Antibody-Producing Cells↗
PubMed1975

Receptors for IgG molecules on human lymphocytes forming spontaneous rosettes with sheep red cells.

A mixed rosette technique with sheep red blood cells (SRBC) and ox erythrocytes heavily coated with rabbit antibody (EA) was employed to simultaneously identify human peripheral blood T lymphocytes and IgG receptor-bearing cells. The findings of a noticeable proportion of "mixed rosettes" in peripheral blood lymphocytes freshly drawn from normal individuals and of an even higher number of these mixed rosettes in cell suspension kept in culture media supplemented with fetal calf serum provide evidence for the capacity of human T cells to express membrane receptors for antigen-antibody complexes.

Binding Sites↗
PubMed1975

Lymphocyte membrane receptors in human lymphoid leukemias.

Membrane-bound immunoglobulins, receptors for the Fc fragment of IgG and receptors for the third component of human or murine complement were used as B cell membrane markers to study peripheral blood lymphocytes from twenty-two patients with chronic lymphatic leukemia (CLL), five patients with acute lymphoblastic leukemia (ALL) and one patient with Sézary syndrome. The capacity of human T cells of forming "spontaneous rosettes" with sheep erythrocytes was employed as T cell membrane marker. In nineteen out of twenty-seven CLL or ALL cases tested a larger percentage of cells than that found in normal individuals expressed at least one of the three B cell membrane markers studied. In the patient with Sézary syndrome the percentage of cells forming "spontaneous rosettes" with sheep erythrocytes was larger than the normal, while cells bearing B cells markers were below the normal values.

Binding Sites↗
PubMed1975

Expression of a receptor for IgM by human T cells in vitro.

The capacity of human peripheral blood lymphocytes (PBL) to bind antigen-IgG antibody (EA(IgG)) and antigen-IgM antibody (EA(IgM)) complexes was investigated using a rosette technique with ox erythrocytes coated with rabbit IgG or IgM antibody. It was found that while EA(IgG)-rosette-forming cells (RFC) were detected on PBL freshly drawn from normal individuals, EA(IgM)-RFC were present only in suspensions kept in culture for 24 h in mediá supplemented with sera containing very low or no amounts of IgM. Experiments of simultaneous detection of EA(IgG)-RFC or EA(IgM)-RFC and other membrane markers for human T or B cells together with experiments on purified T or B cell populations indicated that EA(IgG)-RFC were formed by both T and B cells, while T cells only were capable of EA(IgM) rosette formation. The specificity of the receptors for IgG and IgM was determined by studying the inhibitory capacity of purified human IgM and IgG in the rosette assay. The receptor for IgG was inhibited by IgG and not by IgM, while the reverse was true for the receptor for IgM.

Antigen-Antibody Complex↗