Inhibition of mitosis of lymphocytes from human adults by lymphocytes from human newborns

Autologous red cells derived from cord blood: collection, preparation, storage and quality controls with optimal additive storage medium (Sag-mannitol)

To investigate whether packed red cells (PRCs) prepared from autologous cord blood-packed red cells (AC-PRCs) could be used as an alternative for homologous-packed red cells (H-PRCs), we developed a system to collect and prepare AC-PRCs and determined standard storage parameters during 35 days of storage in extended storage medium (Sag-mannitol). We collected and fractionated cord blood from 390 newborns. The amount and quality of the AC-PRCs were analysed. The bacterial contamination rate was 1.84%. Twelve AC-PRCs were stored for 35 days, and standard laboratory parameters were measured at day 1 and day 35. The initial laboratory parameters of the AC-PRCs were similar to the parameters of the H-PRCs. After 35 days, the AC-PRCs displayed an increased haemolysis rate compared to H-PRCs (1.1 versus 0.2%) and also a significant decreased adenosine triphosphate value (1.2 versus 2.3 micromol L(-1)). Haemoglobin, haematocrit and pH were comparable in both groups. AC-PRCs meet the quality criteria for H-PRCs after 35 days. Utilizing a closed collection system for cord blood and an extended storage medium will increase safety and quality and facilitate the routine transfusion of autologous red cells derived from cord blood.

Neonatal lymphocytes dominate against lymphocytes of their own mother but not against allogenic maternal or adult lymphocytes in bidirectional mixed lymphocyte cultures

OBJECTIVE

Recent studies have shown a regular prenatal transfer of maternal immunocompetent cells into the fetal circulation. However, these cells engraft and proliferate only in a few exceptional cases if the fetus reaches an immunocompetent state. Thus the fetus has to have an immunologic defense mechanism against the engraftment of maternal cells. In the current study we investigated whether the fetus has such an immune defense and whether this defense mechanism specifically attacks cells of the mother.

PATIENTS, MATERIAL AND METHODS

Blood samples were obtained from 15 mothers and 15 newborns directly after delivery. We compared individual vitality and spontaneous cytotoxicity between fetal and maternal lymphocytes in a cell ratio of 1:1 in nonstimulated bidirectional mixed lymphocyte cultures (MLC). The distribution of each cell population within the MLC was visualized by fluorescence in situ hybridization and X/Y-DNA probes. This was compared to MLCs between unrelated fetal and maternal as well as between unrelated adult lymphocytes.

RESULTS

After 72 h, a significant cell shift was observed only in the MLC with neonatal lymphocytes mixed with cells of their own mother; there was a significantly higher number of neonatal cells (0.71 vs. 0.29) present. All other groups continued to have a cell distribution of 1:1.

CONCLUSION

Our results show that neonatal lymphocytes specifically dominate against maternal but not allogenous maternal or adult lymphocytes in nonstimulated bidirectional MLCs.

Serotonergic 5-HT1A receptors regulate a cell contact-mediated interaction between natural killer cells and monocytes

Autologous monocytes irreversibly suppressed functions of human natural killer (NK) cells including baseline and lymphokine-induced cytotoxicity, antibody-dependent cellular cytotoxicity (ADCC), and interleukin-2 (IL-2)-induced proliferation. The suppression of these NK-cell functions was cell contact-dependent and could be evoked only by purified monocytes, recovered directly from peripheral blood by countercurrent centrifugal elutriation (CCE). The presence of monocytes also induced the disappearance of CD16 and CD56 antigen on CD3- NK cells (CD3-/16+/56+-->CD3-/16-/56-). By contrast, T-cell proliferation and the expression of CD3 on CD56- T cells were not susceptible to cell contact-mediated suppression by monocytes. The biogenic amine serotonin abrogated monocyte-induced suppression of NK-cell functions as well as down-modulation of CD16/56 NK-cell antigen. Serotonin thus markedly augmented baseline and lymphokine-induced NK-cell cytotoxicity, ADCC, and NK-cell proliferation, and maintained the expression of NK-cell surface antigens in the presence of elutriated monocytes. The effect of serotonin was mediated by 5-HT1A-type serotonin receptors (5-HT1AR) as indicated by mimicry exerted by 5-HT1AR agonists such as 8-OH-DPAT and (+)-ALK, partial antagonism by the 5-HT1AR antagonists pindolol and cyproheptadine, and lack of antagonism by the 5-HT2R antagonist ketanserin or the 5-HT3R antagonist ondansetron. Our data are suggestive of a cell-to-cell-mediated mechanism by which monocytes down-modulate NK-cell function and phenotype and its serotonergic regulation.

Regulation of the natural killer cell response to interferon-alpha by biogenic amines

Monocytes, recovered from human peripheral blood by counter-current centrifugal elutriation (CCE), suppressed baseline natural killer (NK) cell cytotoxicity (NKCC) and rendered NK cells resistant to activation of cytotoxicity by human recombinant interferon-alpha (IFN-alpha) by a cell contact-dependent mechanism. Monocyte-induced suppression of resting and IFN-activated NK cells was abrogated by the biogenic amines histamine [via H2-type receptors (H2R)] and serotonin [via 5-HT1A-type receptors (5-HT1AR)]. Our data are suggestive of a monocyte/NK cell interaction that is subject to regulation by biogenic amines.

Immunology of pregnancy: towards a unifying hypothesis

The variable findings of hormonal-immunoregulation and the variable cellular and humoral immune responses in pregnancy have been considered in relationship to the physiological response. From such considerations it appears that the peripheral blood lymphocyte/leukocyte response in pregnancy is not important, but rather the local uterine immune response at implantation and throughout pregnancy. It is proposed, and evidence is presented, that a normal allogeneic immune response is initiated at the time of implantation of the blastocyst. This immune response regulates the invasive nature of the trophoblast and initiates the first stage of parturition. The initiation and maintenance of this immune response is based on an interplay between maternal and paternal HLA and trophoblast antigens. In the case of HLA-incompatible donor-recipient blastocyst transplants, a more pivotal role for immunoregulation by trophoblast antigens is proposed. This is because it is considered that the local uterine immune response suppresses the expression of allogeneic HLA. This concept is further developed in terms of haploid HLA suppression on maternal and fetal lymphocytes that cross the placenta. This is considered to allow the interaction of these lymphocytes with each other and explains maternal transfer of cell-mediated immunity.

Cell-to-cell mediated inhibition of natural killer cell proliferation by monocytes and its regulation by histamine H2-receptors

Human peripheral blood monocytes, recovered by counter-current centrifugal elutriation, suppressed interleukin-2 (IL-2)-induced proliferation of autologous lymphocytes, recovered from low density Percoll fractions. Cell sorting experiments, analysis of phenotype of proliferating cells, and removal of defined cellular subsets by complement cytotoxicity revealed that IL-2-induced proliferation was confined to CD3-/16+/56+ natural killer (NK) cells. Monocyte-induced suppression of NK-cell proliferation was completed within 1 h of incubation with monocytes and unrelated to the formation of prostaglandins or other intermediary factors. The biogenic amine histamine, acting via H2-type histamine receptors (H2R) on monocytes, completely counteracted the monocyte-mediated suppression of IL-2-induced NK-cell proliferation. Our data are suggestive of a H2R-regulated, cell-cell-mediated mechanism by which monocytes down-modulate NK-cell proliferation.

Monocyte-induced down-modulation of CD16 and CD56 antigens on human natural killer cells and its regulation by histamine H2-receptors

Human natural killer (NK) cells carry CD16/FcR and CD56 cell-surface Ag but lack the T-cell marker CD3. Here we show that incubation of resting human NK cells with CD3-/16+/56+ phenotype with autologous monocytes induced the disappearance of CD16 and CD56 cell-surface Ag on NK-cells but did not affect CD2 or CD3 Ag expression on T-cells. Monocyte-induced down-modulation of NK-cell-surface Ag was cell-contact dependent and induced only by freshly isolated monocytes, recovered from peripheral blood by counter-current centrifugal elutriation. Adherence of monocytes abrogated the capacity to induce down-modulation of NK-cell-surface Ag. The biogenic amine histamine dose-dependently reversed the monocyte-induced down-modulation of CD16 and CD56 on CD3- NK-cells. The effect of histamine was mediated by H2-type receptors on monocytes. The data presented are suggestive of a cell-cell-mediated interaction between monocytes and NK-cells which modulates surface expression of NK-cell Ag and its histaminergic regulation.

Neonatal T4+ lymphocytes: analysis of the expression of 4B4 and 2H4 antigens

Using monoclonal antibodies anti-2H4 and anti-4B4 we investigated by double immunofluorescence and immunorosette technique the presence of cells displaying the helper-inducer and the inducer of suppression phenotype among T4+ cord blood cells. The analysis of the estimated frequencies of subpopulations of T4+ cells shows that a high percentage of T4+ cord blood cells can coexpress both antigens in comparison to adult. Furthermore the percentage of T4+ cells with helper-inducer phenotype (2H4-4B4+) is significantly lower than that in the adult, while the percentage of T4+ cells with suppressor-inducer phenotype (2H4+4B4-) although higher, is not significantly different. These findings suggest that the relative immunoincompetence observed in the newborn may result from a variety of mechanisms including a low percentage of helper-inducer (4B4+2H4-) T4+ lymphocytes possibly also associated to an increased number of suppressor-inducer T4+ cells (2H4+4B4-).

Cord serum inhibits allogeneic mixed lymphocyte reaction and stimulates lymphokine production

An inhibitory activity on the two-way allogeneic mixed lymphocyte reaction (MLR) was detected in maternal and cord serum at delivery. The inhibitory effect of the maternal serum was found to be more pronounced and was detected in almost all sera tested, whereas the inhibitory capacity of cord sera was observed in only 70% of the cases. In addition, a lower stimulatory activity for interleukin-2 (IL-2) production was found in the maternal serum, suggesting an additional mechanism for the suppression of the maternal immune system during pregnancy. On the other hand, a higher stimulatory activity for IL-2 production was observed in cord serum as compared with adult normal serum. The possibility that a fetal humoral factor is involved in the regulation of the immune system via the stimulation of IL-2 production is discussed.

Phenotypic and cytotoxic characteristics of the immune cells of the human placenta

Despite some functional impairment of the newborn's T-cell immune system, most infants survive the intrauterine and perinatal period without succumbing to infection or maternal lymphocyte engraftment. The placenta may play a crucial role in protecting the infant from microbial and histocompatibility antigens. Accordingly, we studied phenotypic and functional capacities of placental cells. Placentas were obtained from uncomplicated pregnancies. Matched cord blood and maternal peripheral blood were also obtained in many instances. Fresh minced placental tissue was washed and digested with collagenase and DNase and mononuclear cells were obtained by density gradient centrifugation. The average yield was 10(6) cells/g of tissue with greater than 80% viability. Chromosome analysis of five placental preparations indicated that these cells were of fetal rather than maternal origin. The isolated placental cells consisted of trophoblasts, lymphocytes (74 +/- 3%), monocytes (16 +/- 3%), and granulocytes (8 +/- 2%). E-rosette forming cells (T cells) made up 65 +/- 2% and surface membrane immunoglobulin positive cells made up 8 +/- 1% of the placental mononuclear cells. Fluorescent activated analysis of the mononuclear cells indicated less Leu 4-positive cells (Pan-T) 43 +/- 3%, and less Leu 3-positive (T-helper cells) (25 +/- 2%), than cord and maternal cell preparations. Leu-2, DR, and B1 positive cells were similar to those in cord and maternal blood. Leu 7 and especially Leu 11 positive cells, markers for natural killer cells, were abundant in placental cells, making up 4 +/- 0.7% and 20 +/- 3%, respectively. The Leu 7/Leu 11 ratio of the placental cells was different from either the maternal or cord blood cells. Natural killer activity of placental cells against a K562 natural killer target was low, despite the abundance of cells with NK markers. The K562 activity was low in the placental cells, similar to the low NK activity of maternal and cord cells. Molt 4f killer activity was near normal. Lectin-dependent cytotoxicity using an EL-4 cell target plus PHA was low in placentas, compared to normal, maternal, or cord cell cytotoxicity. Matched samples indicated that LDCC activity was mother greater than cord greater than placenta. Antibody-dependent cytotoxicity (Raji target) of placental cells showed low activity, and again the paired studies indicated that normal controls greater than maternal greater than cord greater than placenta cytotoxicity.(ABSTRACT TRUNCATED AT 400 WORDS)

Human fetal/neonatal suppressor activity: relation between OKT phenotypes and sensitivity to prostaglandin E2 in maternal and neonatal lymphocytes

T lymphocytes from human fetuses and newborns strongly and spontaneously suppress various adult cell functions (i.e. T-cell proliferation, B-cell differentiation, and Ig synthesis). The precise phenotype of the suppressor cell is controversial. In this investigation we use cord T-cell subsets negatively selected by the panning technique or by complement-mediated lysis using the monoclonal antibodies OKT4 and OKT8. Cord T cells deprived of the OKT4+ subpopulation exerted only a marginal suppressor activity (12 +/- 7 as compared to 73 +/- 4% of unfractionated T cells) on the proliferation of maternal cells in our PHA-stimulated co-culture assay using sex chromosomes as markers for dividing cord (male) and maternal cells. The suppressive effect was direct, i.e. not mediated by induction of maternal OKT8+ suppressor effector cells. Cord and maternal T-cell subsets were also tested for their sensitivity to exogenous prostaglandin E2 (PGE2) at doses varying between 1.4 X 10(5) and 1.4 X 10(9) M. Both maternal OKT4- and OKT8- T-cell subsets were highly sensitive to suppression by PGE2. In contrast, cord OKT8- T cells were essentially nonsensitive at all doses of PGE2 used, whereas cord OKT4- T cells were significantly suppressed at four out of five concentrations tested (1.4 X 10(6) through 1.4 X 10 (9). Our results suggest a direct correlation between the phenotypes of the cord-suppressor and maternal-target T cells and their sensitivity to PGE2.

Human cord blood suppressor T lymphocytes: I. Phenotype and target of the inducer of suppressor cell factor

The present study examines the characteristics of the cord suppressor T cells and their targets. When an inducer of suppressor T cell factor (TisF) from culture supernatant of alloantigen-activated cord lymphocytes was used as a source of suppression, adult lymphocyte response to soluble antigen candidin, alloantigens, and pokeweed mitogen were all suppressed. These results suggest that TisF acts primarily on T cells in an antigen-nonspecific fashion. Furthermore, preculture T cell irradiation, but not T8+ cell depletion, of adult lymphocytes abrogated the suppressive effect of TisF on the PWM-stimulated IgG production, suggesting that the target of TisF belongs to the radiosensitive T8-(T4+) T cell subset. When different cord T cell subsets were tested for suppressor activity, only radiosensitive T4+ cells were capable of suppressing IgG production by adult lymphocytes. Neither preculture T8+ cell depletion nor irradiation of adult T cells affected the suppression. Taken together, these results suggest that the suppressor activity of cord T cells originated from an inducer of suppressor cells that activates radiosensitive T4+ suppressor effector cells through TisF. In turn, these effector cells act on either radioresistant T4+ helper T cells or B cells or both.

Rat pregnancy immunoregulatory circuits are progestation hormonal status, decidual tissue, embryo-trophoblast and late pregnancy changes dependent

We have tested the spleen cells of rats for their reactivity to mating and unrelated (third party) strain alloantigens during pregnancy, pseudopregnancy, and traumatic deciduoma installation. By cytotoxic T-lymphocyte assays, after 7-day one-way mixed lymphocyte cultures (MLC), we detected the presence of many immunoregulatory circuits among rat pregnancy and postpartum. They are progestation hormonal status, decidual tissue, embryo-trophoblast, late-pregnancy-parturition-associated changes, and lactation-hormonal-status dependent.

Monocyte chemotactic factor production in mixed cultures of maternal and neonatal human lymphocytes

The immunological interaction between related maternal and neonatal human lymphocytes was investigated by assaying monocyte chemotactic factor production in mixed cell culture. Lymphokine was detected in a significantly lower proportion of maternal-neonatal cell cultures compared to mixed cultures of cells from unrelated adults and/or neonates. It is possible that a reduced inflammatory mediator production at the feto-maternal interface may contribute to the survival of the fetal allograft.

Comparative analysis of the suppression by cord blood mononuclear cells of adult and neonatal lymphocytes

The spontaneous or in vivo generated suppressor cell activity of adult and cord blood has been quantitated and compared in a system that examines the regulation of the T-cell response to mitogen. We confirmed previous findings that spontaneous suppressor cell activity is stronger in cord blood. This is only true, however, in a system that uses adult lymphocytes as responder cells. Cord blood responder cells are significantly more resistant to suppressor signals than are adult cells. Thus, the influence of cord blood suppressor cells on cord blood effector cells is equivalent to that seen in similar cocultures containing only adult cells. Spontaneous suppressor cell activity decreases rapidly among cultured adult cells but remains unaffected in cultures of cord cells for at least 4 days. Suppressor cell activity induced by concanavalin A (Con A) was significantly greater with adult cells. The sum of the spontaneous and Con A-induced suppressor cell activity among both cord and adult mononuclear cells was identical, indicating that the total potential suppressor cell function of the two populations is similar and that assays of spontaneous or Con A-induced suppressor cell activity are likely to be examining the same cell population. These findings strengthen the hypothesis that while fetal immunoregulatory cells may be potent suppressor of maternal (adult) lymphocytes, internal (fetal) balance is maintained by having responder cells relatively resistant to these fetal suppressor cells.

Regulation of the immune response by prostaglandins

Of all the arachidonic acid metabolites, only prostaglandin E (PGE) has been shown to have a clear role in the regulation of cellular and humoral immune responses. In cellular immune responses such as T cell proliferation, lymphokine production, and cytotoxicity, PGE usually acts as a feedback inhibitor of the response. This is also true of macrophage and natural killer cytotoxicity. In some instances PGE is responsible for cellular activation rather than inhibition. This is clearest in the control of humoral immunity, where PGE production is a necessary component in the generation of some type of T suppressor cells. Disturbances in immune function found in several human conditions and diseases have been linked to changes in PGE mediated immunoregulation. Either increased production of PGE or increased sensitivity to PGE results in depressed cellular immunity. Conversely drugs which inhibit PGE production act as stimulants of cellular immune function in vitro and in vivo.

Strong suppression by mononuclear leukocytes from cord blood of human newborns on maternal leukocytes associated with differences in sensitivity to prostaglandin E2

We have tested peripheral mononuclear leukocytes (PML) from the cord blood of newborns, from sera of their mothers, and from sera of nonrelated nonpregnant adult women for sensitivity to suppressive exogenous prostaglandin E2 (PGE2). Endogenous PG production was simultaneously inhibited by indomethacin 2.8 microM. The phytohemagglutinin-stimulated (PHA-simulated) uptake of tritiated thymidine (3H-TdR) by PML from the mothers and the nonpregnant women was suppressed by the exogenous PGE2 at a concentration of 1.4 x 10(-8) M, 100 times less than the one required to suppress the PML from newborns (1.4 x 10(-6) M). In addition, 1.4 x 10(-7) M or less of PGE2 reversed the suppression of neonatal PML to stimulation. The maternal PML were reversed into stimulation at 1.4 x 10(-9) of exogenous PGE2. The amount of endogenous PGE2 synthesized by 1 x 10(6) fresh, nonstimulated neonatal PML according to gas chromatography-mass spectrometry assay was 5 ng (1.4 x 10(-8) M). The synthesis increased to 27 ng/10(6) cells after 18 hours' incubation. These concentrations are similar to the ones of exogenous PGE2 at which neonatal PML were slightly stimulated but the maternal cells were still suppressed. Preincubation for 18 h at 37 degrees C decreased the PGE2 induced suppression of the adult PML but did not change the response of the neonatal PML.

Differences in binding sites for prostaglandin E2 on mononuclear leucocytes from human newborns and from their mothers

Binding of [3H]prostaglandin E2 (PGE2) to peripheral mononuclear leucocytes (PML) from newborns and their mothers was studied. Specific binding of PGE2 to both maternal and neonatal PML was found. The binding was maximal after 15 min of incubation at 37 degrees C and specific for PGE1 and PGE2 versus PGA1, PGF1 alpha, and PGF2 alpha. The amount of PGE2 specifically bound to neonatal PML was about 30% of the amount bound to maternal PML. The average number of binding sites for PGE2 on maternal PML was calculated to 1800 per cell, and the dissociation constant (KD) was 6.5 X 10(-9)M. The corresponding figures for neonatal PML could not be calculated owing to the low number of binding sites on those cells. After preincubation for 18 h the binding of PGE2 to maternal PML was decreased and equalled that of PGE2 to neonatal PML, whereas neonatal PML were unaffected by preincubation. These results indicate that differences in sensitivity to suppression by PGE and the effect of preincubation may be linked to differences in binding of PGE.

Conversion of arachidonic acid in human maternal and neonatal mononuclear leukocytes

The metabolism of exogenous [1-14C]arachidonic acid in neonatal and maternal peripheral mononuclear leukocytes was studied. Both neonatal and maternal leukocytes converted arachidonic acid to hydroxy acids and to prostaglandin E2, but small amounts of PGF2 alpha and thromboxane B2 were also found. In addition a polar arachidonic acid metabolite with conjugated double bonds was identified in the supernatant from both maternal and neonatal leukocytes. This might be a leukotriene, but further attempts at biochemical characterization are necessary in order to confirm this.

Easily suppressed lymphocytes and absence of cytotoxic antibody in three women with habitual abortion

This investigation involves 3 women with habitual abortion and 2 women with multiple normal pregnancies. Extensive clinical investigations failed to reveal any cause for the abortions. All husbands were ABO-compatible with their respective wives. The women shared three, two, and zero of five identified HLA-A antigens with their respective husbands. None of the women had any cytotoxic antibody. Lymphocytes from all three women reacted normally in one-way mixed lymphocyte cultures to their husbands' alloantigens. Cell-mediated lympholysis was similar in couples with habitual abortion and in those with repeated normal pregnancies. The women's lymphocytes' proliferation was significantly suppressed by lymphocytes from their husbands and by those from most male controls in two-way mixed lymphocyte culture and double chamber experiments. Two women with 6 and 5 live-born children, respectively, served as controls. Their lymphocytes were not suppressed by lymphocytes from their respective husbands or by those from most male controls in two-way mixed lymphocyte cultures. Their reactions in one-way mixed lymphocyte cultures and in cell-mediated lympholysis, however, did not differ from those of the women with habitual abortion.

Immunologic and epidemiologic aspects of varicella infection acquired during infancy and early childhood

The development of varicella zoster infection was studied in a population of infants under one year of age during three outbreaks of varicella in a semi-closed domiciliary institution for infants in Japan. Over a period of four years, many residents ranging in age from 27 days to 32 months were tested for cutaneous reactivity to VZV antigen, and VZV-specific antibody activity before, during, and after each outbreak of varicella. Of these, 85 subjects developed clinical varicella, with an overall attack rate of 100% for all susceptible subjects. All the infants under 2 months of age were infected following such exposure, despite the presence of pre-existing maternal antibody. The degree of cutaneous involvement appeared to be milder (less than 20 vesicles) in infants less than 2 months of age, and severe cutaneous disease (with over 300 eruptions or confluent rash) occurred more frequently in subjects 2 to 11 months of age. Pre-existing antibody did not prevent development of illness, or alter the degree of antibody or cellular immune response to subsequent infection. However, the peak cutaneous reactivity to VZV antigen after infection was found to be significantly lower in infants under 2 months of age.

Respective roles and interactions of T-lymphocyte and PGE2-mediated monocyte suppressive activities in human newborns and mothers at the time of delivery

Recently the concept of a poorly functional humoral immune response in the newborn was proposed. Data have been presented indicating that the impaired newborn B cell maturation, as shown in vitro in a pokeweed mitogen-induced B cell maturation system, is due both to an immaturity of lymphocyte subsets and to an increased suppressive T activity. In the present work, we present evidence that there exists a predominance of a naturally occurring T lymphocyte suppressive activity in the cord blood in that the removal of the suppressive activity by irradiation allows a normal maturation of newborn B cells. Such normal maturation of newborn B cells can also be obtained using mixed cultures of adult T cells and newborn B cells. Newborn suppressor T cells belong to both EA gamma (+) and EA gamma (-) fractions, and it is not known whether these two groups do or do not belong to different subsets. The PGE2-dependent monocyte suppressive activity does not play any role in the suppression observed in newborns since newborn monocytes are poorly suppressive and since they produce a smaller amount of PGE2 than adult monocytes. Some observations suggest, on the contrary, that the suppressive T lymphocytes can regulate the level of the PGE2-dependent monocyte suppressive activity. It should be noticed that similar observations about T lymphocyte and PGE2-dependent monocyte suppressive activities have been made at the same time using mothers' cells. These observations suggest the possibility that such changes in B cell immune regulation may result from an interaction between maternal and fetal lymphoid cells.

Dysfunctions of pokeweed mitogen-stimulated T and B lymphocyte responses induced by gammaglobulin therapy

Lymphocytes obtained from nonimmuno deficient children treated with commercially available preparations of gammaglobulin failed to proliferate and to mature into plasma cells in vitro after stimulation with pokeweed mitogen. The influence of the treatment on lymphocyte functions varied according to the cell population considered. A T helper cell activity was detected in these patients but only in the cell subset bearing receptors for IgG after irradiation. T lymphocytes exerted a suppressive effect that disappeared after irradiation or incubation at 37 degrees C. The suppressive cells were found among E rosette-forming cells depleted of leukocytes bearing receptors for IgG. Their suppressive effect was expressed only in the presence of normal radioresistant T lymphocytes that did not bear Fc receptors for IgG. Similar dysfunctions could be induced in vitro by incubation of normal T and B lymphocytes with gammaglobulin preparations. Because F(ab)'2 fragments or deaggregated preparations of gammaglobulin failed to activate T suppressor lymphocytes, this activation was likely triggered by attachment of Fc portion of denatured IgG to the corresponding membrane receptor. This activation step was prostaglandin E(2)-dependent, suggesting that activated monocytes were involved in the activation process. B lymphocyte responses appeared directly inhibited by attachment of denatured gammaglobulin on membrane Fc receptor. Our observations suggest that immunological effects of gammaglobulin therapy are not limited to antibody transfer, since it also induces subtle modifications of in vitro pokeweed mitogen-stimulated T and B cell responses. These modifications must be considered in interpreting results obtained in immunodeficient patients investigated under gamma-globulin therapy.

Polyclonal activation of human peripheral blood B lymphocytes by formaldehyde-fixed Salmonella paratyphi B. I. Immunoglobulin production without DNA synthesis

A "new" polyclonal activator of human peripheral blood B cells, formaldehyde-fixed Salmonella paratyphi B, is described. This bacterium does not stimulate cell proliferation as measured by incorporation of tritiated thymidine but does stimulate a subpopulation of B cells to secrete large amounts of IgM, IgG, and IgA in 7-day cell cultures. The immunoglobulins (Ig) produced by cells responding to S. paratyphi B are not specific antibodies against the bacterial antigens. In comparison with other B cell activators (pokeweed mitogen, Staphylococcus aureus Cowan I, and lipopolysaccharide), S. paratyphi B stimulation produced greater amounts of IgM but less IgG than pokeweed mitogen (PWM) or S. aureus Cowan I; lipopolysaccharide failed to stimulate significant Ig production on day 7 in most cases. In addition, the response to S. paratyphi apparently did not require T cell collaboration. These results suggest that the B cell subpopulation(s) responding to S. paratyphi B may be more differentiated B cells than those responding to either PWM or S. aureus Cowan I. Peripheral blood mononuclear cells from five patients with common variable immunodeficiency without evidence of abnormal suppressor T cells or monocytes failed to respond to S. paratyphi B, whereas cells from two of the same patients responded well to S. aureus Cowan I and partially to PWM. Thus, S. paratyphi B appears to be superior to other B cell activators for studies of B cell function in normal and abnormal states.

Cellular mechanisms of restricted immunoglobulin formation in the human neonate

The functional capacity of human neonatal B lymphocytes has been investigated by in vitro methods using T lymphocyte-dependent (pokeweek mitogen, PWM) and -independent (Epstein-Barr virus, EBV) polyclonal B cell activators. B cell activation of single cells was detected by class-specific immunoglobulin (Ig) secretion using a reversed hemolytic plaque assay. It was found that neonatal B cells were triggered to secretion of IgM by EBV, with a magnitude comparable to adult levels, but that, in contrast to B cells from adults, they did not secret IgG. Cord lymphocytes did not secret Ig although they displayed a sizable DNA synthetic response to PWM. Using cell separation and culture experiments, it was shown that (allogeneic) adult T lymphocytes could restore cord B cell responsiveness to PWM and that cord T lymphocytes could not cooperate with adult B cells. In addition to this immaturity of cord T helper function for antibody synthesis, we found cells in the cord T cell-enriched fraction which inhibited the polyclonal response of adult lymphocytes to both PWM and EBV. These lymphocytes suppressed adult B lymphocytes directly but appeared ineffective against neonatal B lymphocytes themselves. The nature of these suppressing cells and their possible role in the fetal/maternal relationship are a matter of speculation.

A population of human cord blood mononuclear cells with surface alpha fetoprotein

Suspensions of mononuclear cells from adult peripheral blood (PBL) and mononuclear cells from cord blood (CBL) were examined for the presence of surface alpha-fetoprotein (AFP) using a fluoresceinated F(ab')2 fragment of rabbit IgG anti-human AFP. The mean proportion of CBL with AFP was increased (10%) when compared with PBL (1%) although some CBL specimens did not demonstrate such an increase (range 0--15%). The presence of AFP on CBL could be either due to cytophilic AFP attached to a unique surface receptor or intrinsic AFP synthesis. The following observations could not distinguish between these two possibilities: (1) After treatment with trypsin, only minor reappearance of surface AFP could be observed in AFP-free medium in contrast to the larger numbers observed in medium containing AFP. Such selective reappearance depending on the media could be related to either cytophilic attachment of heterologous or homologous AFP or preferential stimulation of intrinsic AFP synthesis. (2) The reappearance of AFP positive CBL following trypsin treatment and incubation in media with or without AFP containing sera was inhibited by cyclohexamide. Such inhibition could be due to inhibition of synthesis of an AFP surface receptor or intrinsic AFP. (3) The shedding of surface AFP observed at 2--4 degrees C could be due to release of exogenous cytophilic AFP or the continued "turnover" of intrinsic AFP without concomitant AFP synthesis due to the cold temperature. Finally, the removal of AFP positive cells via selective depletion of B cells using bead columns coated with IgG-anti-IgG and the absence of depletion of AFP positive cells after successive gradient centrifugation of E-rosettes and cells with IgG-Fc receptors are consistent with the identity of AFP positive CBL as cells without IgG-Fc receptors or lymphocytes without conventional T-cell markers as defined by E-rosettes.

Mitosis of maternal lymphocytes in the presence of fetal cells: possible implication in prenatal diagnosis from fetal blood samples

The suppression of proliferation of maternal lymphocytes by the lymphocytes of their own male newborns have been tested in a PHA-induced two-way stimulation system. The mixed lymphocyte cultures of 6 out of 12 such mothers/son pairs had 23--50% metaphases with 46,XX karyotype. In 2 more cases 10% maternal metaphases have been observed. Hence, it appears that fetal lymphocytes are unable to suppress the proliferation of maternal cells completely.