PubMed Health⌕ Search

Biomedical subjects

H Frost

Publications and source records attributed to H Frost.

At least 37 records · Page 2Linked to original sources
PubMed1988

Elevation of IgE-binding factors in serum of patients with B cell-derived chronic lymphocytic leukemia.

One hundred nineteen sera from patients with various lymphoproliferative diseases and normal sera were tested by a solid-phase radioimmunoassay (RIA) for their content in IgE-binding factor (IgE-BF), a soluble glycoprotein binding to IgE and derived from low-affinity IgE receptors (Fc epsilon R). Fc epsilon R, recently identified as CD23, are known to be expressed on the surface of B cells at the intermediate stage of differentiation. The results indicate that in all cases of chronic lymphocytic leukemia (CLL) tested (n = 40), IgE-BF levels (45 to 8,656 U/mL) were 3-fold to 500-fold higher than in 24 controls (15.5 +/- 2 U/mL). With a few exceptions, serum IgE-BF levels could differentiate patients with CLL from those with other leukemias or lymphomas. In vitro studies indicated that B lymphocytes isolated from CLL patients produced 8 to 50 times more IgE-BF than did normal B cells (P less than 0.001). IgE-BF level was correlated with the Rai stage of the disease (P = 0.002) and the lymphocyte count (P = 0.041). IgE-BF was purified to homogeneity from one CLL serum sample by a combination of affinity chromatography and reverse-phase high-performance liquid chromatography (HPLC). this IgE-BF proved identical to IgE-BF isolated from the culture supernatant of RPMI 8866 cells, a B lymphoblastoid cell line bearing Fc epsilon R and secreting IgE-BF. Indeed, the two molecules had the same mol wt (25 to 27 kd), the same isoelectric point, and the same tryptic map. We suggest that determination of serum IgE-BF might prove useful for clinical monitoring of CLL.

B-Lymphocytes↗
PubMed1987

Cloning and expression of the cDNA coding for a human lymphocyte IgE receptor.

Low-affinity receptors (Fc epsilon R) and secreted factors (IgE-BF) which bind to immunoglobulins of the IgE isotype play a key role in the regulation of human IgE synthesis. We report here the cloning of a cDNA coding for the Fc epsilon R of the human B-lymphoblast cell line RPMI 8866. The nucleotide sequence of this cDNA predicts a polypeptide with 321 amino acids and a mol. wt of 36,281 daltons. A functional Fc epsilon R capable of binding IgE was expressed in Chinese hamster ovary cells after stable transformation with the cDNA which had been cloned into a mammalian expression vector. Amino acid sequence analysis of IgE-BF purified from RPMI 8866 cells revealed an amino-terminal sequence of 19 residues which coincides with the predicted amino acid sequence of the Fc epsilon R, starting at residues 148 and 150. A computer search with the translated amino acid sequence of the Fc epsilon R revealed a domain of 120 amino acids having striking homology to the human asialoglycoprotein receptors.

Amino Acid Sequence↗
PubMed1987

Purification and partial biochemical characterization of IgE-binding factors secreted by a human B lymphoblastoid cell line.

IgE-binding factors (IgE-BFs) were purified from the culture supernatant of RPMI-8866 cells, a human lymphoblastoid B-cell line expressing IgE receptors. The material, purified by affinity-chromatography on immunoadsorbents coupled to IgE or to monoclonal antibody against IgE receptor, was comprised of two major components with apparent molecular weight (MW) of 25,000-27,000 and 12,000, as determined by SDS-PAGE and silver staining. Only the 25,000-27,000 MW molecules were identified as IgE-BFs, as demonstrated by their reactivity with MabER in the Western blot and the immunoprecipitation assays, and their ability to inhibit rosette formation of U937 cells with IgE- but not with IgG-coated erythrocytes. IgE-BFs were purified to homogeneity by combining affinity-chromatography and either DEAE-ion exchange or reverse-phase chromatography on an HPLC system. Chromatofocusing analysis demonstrated the microheterogeneity of IgE-BFs that were comprised of molecules with isoelectric points ranging from 5.0 to 4.4. IgE-BFs were sensitive to treatment with O-glycosidase but not with N-glycanase. These molecules were resistant to heat and to pH ranging from 2 to 9; their immunoreactivity was lost after treatment with trypsin and pepsin. Papain digestion of purified IgE-BFs generated 14,000-16,000 MW molecules that were still binding to IgE and to MabER.

B-Lymphocytes↗
PubMed1984

Application of the dot immunobinding assay to allergy diagnosis.

The recently developed dot immunobinding assay is operationally simple and facilitates performance of multiple simultaneous assays. Here, its use as the basis for determination of total and allergen-specific IgE is established. For total IgE, the same commercially available polyclonal anti-human IgE was used on the solid phase and as a peroxidase conjugate in the liquid phase. After incubation with a chromogenic substrate, IgE was determined from the color intensity of the resulting dots with a scanning reflectance densitometer. The limit of sensitivity was 50 pg/ml of IgE. Standardized conditions gave the dynamic range 50 to 2500 IU/ml in serum. The IgE measured was not subject to interference by serum components, was labile at 56 degrees C, was soluble at 30% saturation (NH4)2SO4, and was unaffected by anti-human immunoglobulins of other specificity. Coefficients of variation were 0.05 within run, and were 0.1 between run. Comparison with data on sera obtained with the PRIST method yielded a correlation coefficient of 0.96 and a linear regression of slope 1.15. Assays for allergen-specific IgE were established with bee venom and dust mite allergens in the solid phase. The same peroxidase-conjugated antibody was used as for total IgE. Comparisons with comparable RAST assays were performed.

Antibody Specificity↗
PubMed1980

Suppression of experimental allergic encephalomyelitis with thoracic duct lymphocytes.

Thoracic duct lymphocytes (TDL) from Lewis rats immunized 9-10 days previously with basic protein in complete Freund's adjuvant (BP-CFA) failed to induce experimental allergic encephalomyelitis (EAE) in syngeneic recipients. This contrasts with the successful transfer of EAE by lymph node cell suspensions from donors immunized 9 days previously with BP-CFA. Only minor EAE was induced passively by TDL from rats immunized 11-12 days before with BP-CFA. TDL collected 9-20 days after BP-CFA immunization, however, were successful in transferring specific suppression of EAE tested by the lack of disease in the recipients immunized actively with BP-CFA 1 week after the TDL transfer. The data indicate that the thoracic duct contains specific suppressor cells shortly before, during and after the development of clinical EAE.

Animals↗
PubMed1979

Changes in mixed lymphocyte culture-reactive lymphocytes following alloimmunization of single lymph nodes in sheep.

When an "isolated" single lymph node is challenged with irradiated allogeneic lymphocytes, there is a change in the reactivity of the lymphocytes flowing out of the node when they are cultured in vitro in unidirectional mixed lymphocyte cultures (MLC) against the immunizing lymphocytes. These changes in the reactivity of the recipient lymphocytes are shortlived, follow a set time sequence in relation to the cell traffic changes accompanying the immune response, are the property of small lymphocytes and not blast cells, are exhibited by surface Ig-negative cells, and they are specific for the donor lymphocytes. It is suggested that antigen causes the selective retention of antigen-specific lymphocytes within the stimulated node followed by the proliferation and differentiation of large numbers of antigen-specific cells, which then leave the lymph node as small lymphocytes.

Animals↗
PubMed1979

Clonotype patterns of antibodies released by single lymph nodes.

Experimental primary, secondary and tertiary stimulation with streptococcal vaccine of isolated lymph nodes in vivo in the sheep model induces largely persistence of anti-group polysaccharide antibody clonotype patterns with the rare occurrence of additional clonotypes demonstrable after secondary stimulation persisting during the tertiary stimulus. It is not clear whether these additional clonotypes are the products of mutants or whether they pre-existed and were demonstrable only after a secondary stimulus, because of threshold concentrations required for identification. Further, isolated contralateral popliteal and prescapular lymph nodes of individual sheep share completely overlapping clonotype patterns during experimental primary anti-polysaccharide antibody responses indicating an identical repertoire of specific clonotypes under this condition of responsiveness.

Animals↗
PubMed1978

Behaviour of sheep-immunoglobulin-bearing and non-immunoglobulin-bearing lymphocytes isolated by nylon wool columns.

The technique of separating lymphocytes on nylon wool columns has been applied to sheep lymphocytes obtained from efferent lymph. The non-immunoglobulin-bearing (sIg-) lymphocytes which pass through the column were MLR-reactive, responsive only to T cell mitogens, and migrated in vivo like T lymphocytes described in rodents. Immunoglobulin-bearing (sIg+) lymphocytes were MLR-non-reactive, responsive to lipopolysaccharide and migrated in vivo like B lymphocytes in rodents. It is considered that the majority of sIg- lymphocytes obtained in this way are T lymphocytes and the majority of sIg+ lymphocytes are B lymphocytes.

Animals↗
PubMed1977

The appearance of non-specific antibody-forming cells in the efferent lymph draining antigen-stimulated single lymph nodes.

Immunization of single lymph nodes with various antigens led to the appearance of cells in the efferent lymph that secreted antibody specific for the antigen which induced their formation and for a number of unrelated, non-crossreacting antigens. Immunization of single lymph nodes with mitogens led to the appearance of cells secreting antibodies specific for an even greater number of antigens, including one (TNP) that in all probability is not present in the animals' natural environment. When the node was primed with one antigen, a subsequent challenge with an unrelated antigen 12 weeks later led to the appearance of greater numbers of cells containing and secreting antibody against the previously experienced antigen, than was the case in unprimed lymph nodes. These findings indicate that the immune response to antigen provokes the maturation of lymphocytes of specificities unrelated to that of the injected immunogen. Such a mechanism may be important in maintaining immunological memory. Mitogens may directly activate lymphocytes into maturation and expression as antibody-secreting cells, whereas antigens appear to act indirectly.

Animals↗
PubMed1976

The effects of antigen on the migration of recirculating lymphocytes through single lymph nodes.

The increased input of RL into LN starts within 3 h after antigenic stimulation and is due to an increase in the number of RL passing through a LN. It is not associated with an altered transit time through a LN of the majority of RL and it cannot occur in the absence of high endothelial PCV. The immediate decrease in the output of RL from an antigen-stimulated LN is due to a delay in the exit from that LN of RL which had entered the LN before antigen was given. The decrease in cell output from a LN after antigen administration affects blast cells produced within the LN as well as small lymphocytes and is not specific for RL. There are at least two distinct mechanisms controlling the migration of RL through an antigen-stimulated LN. The first controls the increased input of RL which occurs only through high endothelial PCV. The second controls the immediate decrease in cell output, which although it does not occur at the level of the high endothelial PCV, can only occur in organized lymphoid tissue. The increased input of RL into an antigen-stimulated LN and the decreased cell output from the LN can occur independently and are possibly controlled by different mechanisms.

Animals↗
PubMed1976

Antipolysaccharide antibodies of restricted heterogeneity secreted by a single lymph node.

Immune responses which give rise to the synthesis of antibodies of restricted heterogeneity can be reproducibly induced in rabbits and mice by streptococcal polysaccharide antigens (1,2). While these reports have demonstrated clonotype restriction in the immune serum of rabbits and mice, they give little information with respect to the clontype restriction in a single reaction site of organized lymphoid tissue, for example a single lymph node. The kinetics of immune responses in lymph nodes in situ have been studied in sheep using a variety of antigens (3-6), and a substantial body of information is available on the changes in cell output, cell type, and the number of antibody-secreting cells which occur within the efferent lymph of antigen-stimulated lymph nodes. However, there is no information with respect to the amount and the heterogeneity of antibody that is secreted by the lymph node or cells within the efferent lymph. In the present report we have examined the temporal sequence of clonal restriction in the efferent lymph of individual sheep popliteal lymph nodes undergoing an immune response to the streptococcal group A-variant polysaccharide (Av-CHO).

Animals↗