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J Zijlstra

Publications and source records attributed to J Zijlstra.

29 records · Page 2Linked to original sources
PubMed1984

Antigen-induced plaque-forming cell responses in cultures of peripheral blood mononuclear cells of human neonates and infants.

Human cord blood mononuclear cells (CBMC) were stimulated in vitro with a number of T cell-dependent antigens. Antigen-induced B cell activation was measured applying a plaque-forming cell assay for the detection of antigen-specific IgM-secreting B cells. With the exception of diphtheria toxoid, the antigens ovalbumin, sheep red blood cells, Helix pomatia hemocyanin, burro red blood cells, and tetanus toxoid elicited an IgM-plaque-forming cell response in cultures of CBMC to levels obtained for peripheral blood mononuclear cells (PBMC) from adult controls. However, for each antigen used, the antigen dose optimal for the induction of a response was consistently found to be a hundred to a thousand times lower than the concentration of the corresponding antigen optimal for adult PBMC. Longitudinal studies on PBMC obtained from infants between 2 and 30 months of age revealed that a shift of the antigen dose toward concentrations needed to induce plaque-forming cells in cultures of adult PBMC occurs at approximately age 8 months. Our data indicate that various antigens can be used for the in vitro analysis of antigen-specific B cell activation and regulatory T cell functions in studies concerning the ontogeny of the humoral immune response in humans.

Adult↗
PubMed1984

Distinct role of neonatal and adult monocytes in the regulation of the in vitro antigen-induced plaque-forming cell response in man.

Mononuclear cells from human cord blood (CBMC) are able to mount an antigen-specific IgM plaque-forming cell (PFC) response after primary in vitro stimulation with the T cell-dependent antigen ovalbumin (OA). The antigen dose-response relationship for the induction of PFC in cultures of CBMC is represented by a bell-shaped curve comparable to that found for mononuclear cells from adult peripheral blood (adult PBMC). The dose of OA optimal for the induction of a response in cultures of CBMC consistently, however, is 100-fold lower than the antigen dose optimal for adult PBMC (0.03 microgram OA/ml vs 3.0 micrograms OA/ml). Results obtained from co-culture experiments in which semiallogeneic combinations of parental/neonatal lymphocytes and monocytes were stimulated with a variable dose of OA indicate that the adherent cell (AC) plays a pivotal role in the establishment of the optimum antigen dose. From experiments using antigen-pulsed AC, it was concluded that neonatal and adult AC differ in their antigen handling capacity. In the presence of the prostaglandin synthetase inhibitor indomethacin the antigen dose-response relationship for the induction of PFC in cultures of CBMC shifts to an "adult type" of curve. From pulsing experiments it emerges that indomethacin affects the interaction between antigen and monocytes. Indomethacin causes an enhancement of the expression of HLA-DR at the surface of neonatal as well as adult AC; this can be down regulated by the addition of prostaglandin E2 (PGE2). The addition of PGE2 to cultures of adult PBMC leads to a shift of the optimal antigen dose for induction of PFC toward lower concentrations. Although higher levels of PGE2 were measured in the supernatant of cultured neonatal AC compared with adult AC, it seems unlikely that this observation can explain the distinct antigen dose-response relationship for the induction of a PFC response in cultures of CBMC.

Adult↗
PubMed1983

Influence of erythrocyte contamination on the optimal phytohaemagglutinin concentration in Chinese hamster lymphocyte cultures.

Lymphocyte cultures from the Chinese hamster were made with lymphocytes isolated with Ficoll-Isopaque or with Haemaccel. In some experiments the red blood cells (r.b.c.) that remained after lymphocyte isolation were lysed. Optimum phytohaemagglutinin (PHA) concentration for lymphocyte proliferation depended upon the manner in which the lymphocytes were obtained. Lower PHA concentrations were needed for optimum stimulation of lymphocytes isolated with Ficoll-Isopaque than for lymphocytes isolated with Haemaccel. Lysis of the r.b.c. remaining after isolation of lymphocytes with Haemaccel resulted in a decrease of optimum PHA concentration. The optimum PHA concentration depended strongly on r.b.c. contamination, the higher the r.b.c. contamination the higher the optimum PHA concentration. However, only part of the differences found in optimum PHA concentrations can be attributed to r.b.c. contamination.

Animals↗
PubMed1983

Antigen-specific plaque-forming cell response of human cord blood lymphocytes after in vitro stimulation by T cell-dependent antigens.

Mononuclear cells isolated from human cord blood (CBL) of full-term neonates were stimulated in vitro with a dose range of T cell-dependent antigens, i.e. ovalbumin or sheep erythrocytes, and tested for the capacity to mount an antigen-specific plaque-forming cell (PFC) response. Both of the antigens used induced in CBL a PFC response with the same kinetics of PFC formation and of the same magnitude as found in cultures of adult peripheral blood lymphocytes (PBL). However, optimal PFC responses in CBL were obtained at a hundredfold lower concentration of the antigens compared with the optimal antigen doses for the induction of a PFC response in adult PBL. This phenomenon was further investigated with respect to the antigen dose dependency of the activation of neonatal B cells and neonatal regulatory T cells. The induction of a PFC response in CBL at antigen concentrations that were suboptimal for adult PBL showed a correlation with the particular antigen dose requirements for the activation of B cells and T helper cells in neonates. Furthermore, the findings suggest that the decrease of the PFC response in CBL stimulated with supraoptimal doses of antigen was not caused by the induction of unresponsiveness at the B cell level or by interference of pregnancy-associated substances with the PFC response, but was rather the result of the activation of antigen-specific T suppressor cells. Neonatal T suppressor cells were activated at antigen concentrations that generated T helper activity in the adult. Thus, although neonatal B cells possess the intrinsic capacity to mature into antigen-specific PFC, the conditions for effective activation of neonatal T cells regulating the B cell response differ from those for the activation of adult regulatory T cells.

Antigens↗
PubMed1982

Different optimal PHA concentrations for stimulation of Chinese hamster lymphocytes in cultures supplemented with foetal calf serum or horse serum.

Chinese hamster lymphocyte cultures were supplemented with foetal calf serum (FCS) or hose serum (HS). Addition of 2-mercaptoethanol (2-ME) to cultures supplemented with these sera resulted in a marked increase lymphocyte proliferation. The PHA concentrations necessary for optimal lymphocyte stimulation were much lower in cultures supplemented with HS than with FCS. Phytohaemagglutinin (PHA) concentrations optimal for stimulation of a given number of lymphocytes in cultures supplemented with FCS often gave inhibition of similar cultures supplemented with HS.

Animals↗
PubMed1980

Chinese hamster lymphocyte cultures. Relationship between lymphocyte proliferation, cell concentration, culture time and culture area.

Different numbers of Chinese hamster lymphocytes were cultured in microtiter plates with flat-, round- and V-bottomed wells for different culture times. The smallest number of cells could be stimulated in plates with V-bottomed wells. At least 25,000-50,000 cells and a longer culture time than for round- or V-bottomed plates were required for maximal stimulation in flat-bottomed plates. For a given well conformation the optimal day of culture is earlier with higher and later with lower cell concentrations. The optimal culture time for a given number of cells is shortest in V- and longest in flat-bottomed plates. The amount of PHA producing the highest thymidine incorporation for a given number of cells depends upon the well conformation. It decreases with lower cell concentration and increases with longer culture time.

Animals↗
PubMed1980

Genetics of Chinese hamster mixed lymphocyte reactivity.

Two-way and one-way mixed lymphocyte cultures (MLC) with Chinese Hamster peripheral blood lymphocytes were performed. Reduction of the culture surface and additon of 2-mercaptoethanol to the culture medium gives a marked enhancement of the reactivity of low numbers of lymphocytes in the MLC. Genetic analysis of the mixed lymphocyte reactivity (MLR) in the animals studied so far indicates that three or four different alleles are involved. However, not all phenotypes could be traced. The samples of different stocks of Chinese Hamsters in Europe and the United States did not all share the same alleles and the samples were also different as regards the relative frequency of phenotypes. For DNA inhibition in stimulating cells mitomycin C treatment is less suitable than irradiation. Skin graft survival time was longer in animals which showed no MLR than in animals with a positive MLR.

Alleles↗
PubMed1978

Tumor-induced changes in T cell mitogen responses in rats: suppression of spleen and blood lymphocyte responses and enhancement of thymocyte responses.

Concanavalin A (Con A) and phytohemagglutinin (PHA) responses of spleen and blood lymphocytes from tumor-bearing (TB) rats were found to be markedly depressed in 4 different models employing tumors of spontaneous origin. Removal of phagocytic cells from both spleen and blood lymphocyte suspensions led to a complete restoration of the responses, indicating that the decreased responses were not due to intrinsic defects in the lymphocytes. The reduction was shown to be due to the inhibitory effect of an increase in the percentage of phagocytic cells. In addition, TB induced an atrophy of the thymus and a decrease in the number of thymic lymphocytes, mainly due to severe lymphocyte depletion in the cortex. The cells that remained in the thymus exhibited increased responsiveness to PHA and Con A as compared to thymus cells from normal rats. Similar results were found in hydrocortisone acetate-treated rats, suggesting that TB leads to a decrease in nonresponsive, cortical corticosteroid-sensitive thymocytes.

Animals↗
PubMed1977

The influence of the serum/PHA ratio, microplate well shape and 2-mercaptoethanol on the stimulation of different numbers of cells in lymphocyte cultures from the chinese hamster.

Conditions for microculture of Chinese hamster lymphocytes are described which allow measurement of thymidine uptake with 6000 to 1000 lymphocytes per culture. The relationship between degree of cell stimulation, PHA concentration culture surface and cell concentration is described, as well as the influence of addition of 2-mercaptoethanol to the cultures.

Animals↗
PubMed1976

Short-term microcultures of lymphocytes from Chinese hamster peripheral blood.

A microtechnique for the culture of Chinese Hamster lymphocytes is described using Cooke microtiter plates with 100,000 leucocytes in a culture volume of 0.1 ml and a culture time of three days. The culture media used were RPMI 1640 and Trowell T8 supplemented with 20% foetal calf serum (FCS) and 2 mu PHA. The cells were harvested with a Skatron cell culture harvester using glass fibre filters. Various technical aspects of the lymphocyte cultures from the Chinese Hamster are described. The relevance of changes in culture conditions to the variability of culture results was analysed for PHA and FCS concentrations, different culture media, cell concentration, vessel shape and culture duration.

Animals↗