Lymphocyte subpopulations in neonates, young children and adults as detected by six cell surface markers

Quantitation of T cells in venous blood of healthy neonates

Quantitation of T Cells in blood is the part of the diagnostic workup for cellular immunity. Specimens of venous blood were collected within 24 hours of birth from 51 healthy, appropriate for gestational age infants. T lymphocytes were identified on the basis of their ability to form rosettes with sheep erythrocytes. The lymphocytes were harvested from peripheral venous blood, which is considered to be more representative of the immune status in the newborn than the cord blood. In the newborn infants the proportion in T cells was found to be considerably diminished in comparison to previously reported values for adults. Preterm infants, especially those with gestational age of 34 wk or less had significantly lower percentage of T cells in their blood as compared with term infants. The proportion of T cells was statistically reduced in infants weighing 2000 g or less in contrast to those weighing 2500 g or more.

Phenotypic analysis of a large number of normal human bone marrow sample by flow cytometry

Bone marrow aspirates from 48 healthy donors (34 adults, 14 children) were analyzed by flow cytometry (FACS Analyzer) after purification of low-density bone marrow cells (Ld BMC) on a density gradient (d = 1,077) and labelling with 23 anti-hematopoietic cell monoclonal antibodies. Based on physical properties, these Ld BMC could be divided into four different populations called E, My, Mo and L, which comprised 14% +/- 9%, 31% +/- 16%, 10% +/- 5% and 45% +/- 14% of these cells, respectively. The phenotypic analysis of these different populations enabled the identification in E, of erythrocytes (Glycophorin A+, Rhesus D+, but negative for early erythroid differentiation markers such as the transferrin receptor (Tf. R) and the FA6-152 antigen); in My of cells of the myeloid lineage (VIM2+, HLA DR-); in Mo of cells of the monocytic lineage (VIM2+, CD14+) plus some myeloblasts (VIM2+, CD14-, HLADR+) and finally in L of a heterogeneous population including: 1. T lymphocytes labelled to the same extent by CD2, CD3, CD5 and CD6 (28% +/- 10%), B lymphocytes assessed by CD19 and CD20 (12% +/- 8%), Pre-B cells (CD10+ = 8% +/- 7%), less than 5% of "natural killer" cells (CD16+ or Leu7+) and finally, less than 6% of myelomonocytes (CD14+ and/or VIM2+). 2. The erythroid lineage (rhesus D+ = 42% +/- 20%, Tf.R+ and FA6-152+ = 32% +/- 12%). 3. Undifferentiated cells or progenitor cells (CD34+ = 7% +/- 5%). 4. Cells unlabelled by any antibodies (approximately 6%). We observed no difference between bone marrow samples from adults or children, with respect to physical properties, and with all but four immunological markers. A significantly higher proportion of B cells (CD19+ and CD10+) (P less than 0.001) and undifferentiated cells (CD34+ and HLADR+) (P less than 0.02) was observed in children. These data, obtained from a large number of bone marrow samples, could be used to quantify the imbalance of some bone marrow disorders.

Heterogeneity of immune defects in three children with a chronic active Epstein-Barr virus infection

Three children, all girls, showed long-lasting clinical and serologic evidence of chronic active Epstein-Barr virus (EBV) infection. Extremely high serum titers of IgG- and IgA-type VCA antibodies and EA antibodies were present, whereas EBNA antibody titers were in the range of those found in seropositive individuals. All three patients repeatedly showed the presence of nonspecific pokeweed mitogen (PWM)-activatable suppressor cells in the peripheral blood. The analysis of EBV-specific cytotoxic T cells showed that one patient exhibited normal cytotoxicity, whereas a second patient demonstrated no EBV-specific cytotoxicity together with unusually high levels of virus-infected B cells in the blood and lymph node. The third patient repeatedly showed refractoriness of the circulating B cells to EBV infection, probably on the basis of some developmental defect. It was concluded that each patient has his or her own peculiar defect in the virus-host balance, indicating that heterogeneity may underlie the syndrome of chronic active EBV infection in humans.

Hexokinase, phosphofructokinase and pyruvate kinase isoenzymes in lymphocyte subpopulations

In order to study the three regulator enzymes of glycolysis, hexokinase (HK), phosphofructokinase (PFK) and pyruvate kinase (PK), in relation to lymphocyte maturation, lymphocytes of different origin were investigated. Lymphocytes from bone marrow, thymus, cord blood, adult peripheral blood and mitogen-stimulated lymphocytes were investigated. The enzyme activities were determined and the isozyme patterns were studied by means of electrophoresis, kinetic measurements and immunoprecipitation. The young lymphocytes from bone marrow and the mitogen-stimulated lymphocytes could be distinguished from the other lymphocytes by a higher residual HK activity in the presence of the inhibitor glucose-1,6-diphosphate. Peripheral blood T lymphocytes differed from non-T lymphocytes in the PK isozymes distribution. All the cells contained PK type K4 and the hybrid K3M. In T cells a smaller amount of the K isozyme was seen than in non-T cells. The PK residual activity in the presence of alanine was significantly higher in peripheral blood T cells than in non-T cells. Thymocytes are characterised by a larger amount of PFK M-subunits than peripheral blood T and non-T lymphocytes. The stimulation of PFK by the positive effector glucose-1,6-diphosphate was higher in thymocytes than in the peripheral blood lymphocytes.

Immunoregulatory T cell subpopulations in man: dissection by monoclonal antibodies and Fc-receptors

Until now, most of the studies on regulatory T cells have been based on culture systems in which human peripheral blood cells are stimulated by polyclonal stimulators like Pokeweed Mitogen (PWM). Our present contribution, however, deals with T cell-mediated regulation of the antigen-induced B cell activation, which exclusively leads to an antigen-specific IgM production (Heijnen et al. 1979a). Some authors' reports on regulatory activities of T cells, as tested in systems using polyclonal stimulators, differ from ours. This may be due to: a) as a result of polyclonal stimulus, various types of regulatory T cells are activated at the same time b) in contrast to a primary antigen, a polyclonal stimulator induces a rapid proliferation of the various regulatory T cells c) a polyclonal stimulator induces the differentiation of B cells in various maturational stages, that might each require additional or different regulatory signals. For example, Thomas et al. (1981) have shown that freshly isolated T4+ cells can induce suppressor activity in unprimed T8+ cells in the presence of PWM, whereas T4+ cells, precultured for 24 h in the presence of PWM, can exert a suppressor activity themselves without an apparent need for T8+ cells. In the antigen-specific system, however, we have neither been able to detect T suppressor effector activity in a population of primed T4+ cells, nor been able to demonstrate T suppressor inducer activity in unprimed T4+ cells (Heijnen et al. 1982a). Therefore the state of activation of the total T4+ population will dictate the balance of the total T helper and T suppressor activity. As a result of proliferation induced by polyclonal mitogens, small subsets of regulatory T cells, which are functionally undetectable in the primary antigen-specific assay, can expand sufficiently to have a measurable effect. Thomas et al. (1980) have shown that the T4+ suppressor inducer cell in the PWM system is radio-sensitive, which is in contrast with our data in the antigen-specific system. This may imply that we are looking at different subsets of T suppressor inducer cells in these different systems, but it might also indicate that T suppressor inducer cells need to proliferate in order to be able to measurably regulate the large pool of responding cells generated in the PWM system. Apart from such quantitative effects, polyclonal B cell activators like PWM are capable of inducing the differentiation of B cells in various maturational stages (Kuritani & Cooper 1982, Stevens 1982, Peters & Fauci 1983). Since it is highly likely that the regulation of these various B cell subsets might require different regulatory signals, the PWM model might be a very complicated model to study regulatory effects of single T cell subsets.(ABSTRACT TRUNCATED AT 400 WORDS)

Suppression of B lymphocytes in mature newborn infants

The ability of cord blood lymphocytes to secrete immunoglobulins during in vitro culture was investigated by means of a reverse hemolytic plaque forming cell (PFC) assay. Mononuclear cord blood cells did not differentiate into immunoglobulin-secreting cells after stimulation with the polyclonal B lymphocyte activator pokeweed mitogen (PWM), contrary to the findings in normal adults. Mononuclear cord blood cells were then separated into T-enriched and T-depleted blood lymphocyte subsets. When these were co-cultured, the PWM-induced immunoglobulin secretion was still low; following irradiation of the T-enriched cells, the numbers of IgM-PFC but not of IgG- or IgA-PFC increased considerably. The effect of irradiation of the T-enriched cells on the PWM-induced IgM response was dose-dependent, with maximal effect at 2500 rad. It is concluded that the low PWM responses obtained using cord blood lymphocytes are in part due to suppression by radiosensitive T suppressor cells. Following removal of this suppression by means of irradiation, B lymphocytes can be induced to secrete IgM, but not IgG or IgA.

Natural killer cell activity and antibody-dependent cellular cytotoxicity in newborn infants

The ability of lymphocytes from the peripheral blood of preterm and term infants and adult women and men to mediate natural killing (NK) and K cell activity (antibody-dependent cellular cytotoxicity) was analysed in 4 hours 51Cr-release assays. K 562 cells were targets for NK activity. K cell activity was assayed on antibody-coated rat thymocytes. Lymphocytes from adult male donors were significantly more cytotoxic to K 562 cells than were lymphocytes from adult female donors. Lymphocytes from both preterm and term infants had significantly lower NK and K cell activity than lymphocytes from adult donors. During the first month of life no increase in NK activity or K cell activity occurred in 7 infants who were re-examined. It is concluded that neither NK nor K cell activities are fully developed during the first month of life.

Lymphocyte subpopulations in patients with various immunodeficiencies

We have studied patients with various immunodeficiencies for the occurrence of blood lymphocytes bearing six different surface markers: the affinity to sheep erythrocytes (Es) to identify T cells, the presence of surface-bound immunoglobulins (sIg) to distinguish B cells, the affinity to mouse erythrocytes (Em) as a second B cell marker, and the receptors for the Fc part of IgM (IgM-FcR), the Fc part of IgG (IgG-FcR) and for complement (CR). IgG-FcR bearing lymphocytes were present in normal proportions and the same was found for CR-positive lymphocytes. None of the patients with congenital agammaglobulinaemia had sIg-bearing or Em-binding B lymphocytes. Four patients with ataxia teleangiectasia had low B cells and 3 out of 4 also had low proportions of IgM-FcR-bearing (T) cells. A child with partial DiGeorge syndrome did not have a grossly abnormal marker pattern although there appeared to be a shift in the T/B cell ratio in favour of the B cells. In a patient with selective cellular immunodeficiency associated with a purine nucleoside phosphorylase deficiency, who was followed during reconstitution therapy with plasma and red cells, a positive change in the marker pattern was seen. Similar observations were made in a child with combined immunodeficiency during treatment. The findings are being discussed in the light of the current knowledge of the functions and ontogeny of lymphocyte subsets.

Fc receptors on rabbit lymphocytes. Identification and organ distribution of rosette-forming cells; cocapping with surface immunoglobulin

Fc receptor (FcR)-bearing cells were demonstrated using ox erythrocytes coated with homologous IgG-type antibodies (EA gamma) in rabbit peripheral blood leukocytes (PBL) and in various lymphoid organs. Discrimination of the rosette-forming cells (RFC) is carried out after prior ingestion of tetramethylrhodamine isothiocyanate-labeled latex particles and in transmission electron microscopic studies. Most of the nonlymphoid cells (5-10%) in PBL and spleen cell suspensions expose FcR. These nonlymphoid cells are almost absent in other lymphoid organs, except in bone marrow. The average percentage of cells rosetting with IgG-sensitized erythrocytes (EA gamma RFC) in lymphoid cell preparations of the various tissues was as follows: PBL 25%, bone marrow 65%, appendix 37%, spleen 40%, Peyer's patches 44%, thymus 2% and peripheral lymph node 27%. The nature of FcR-bearing PBL was further studied using F (ab')2 anti-IgM, anti-IgA or anti-T cell conjugates. About half of the population of B cells, bearing IgM or IgA express FcR. Moreover, about 80% of the RFC are found within the B cell population. Only a few T cells were found rosetting with EA gamma suggesting that most of the non-B lymphoid RFC are "null" cells. In different lymphoid organs, the percentages of EA gamma RFC and B cells are comparable but not identical A greater part of the EA gamma RFC also expresses the receptor for the third component of complement. After capping of membrane IgM determinants, FcR is located in the same cap on the majority (60%) of the FcR-positive IgM-capped cells.