Expression of 20 alpha-hydroxysteroid dehydrogenase activity in human lymphoid and non lymphoid cells

Expression of 20-alpha-hydroxysteroid dehydrogenase (20 alpha-SDH), a putative T cell marker in the murine system, has been examined in human haematopoietic cells. Higher levels of enzymatic activity were expressed by human peripheral blood mononuclear cells (PBMC) in comparison with thymocytes. When PBMC were fractionated into T and non T cell subsets, the greatest values of 20 alpha-SDH activity were associated with the non T cell population. Cells from bone marrow exhibited lower levels of 20 alpha-SDH than PBMC and thymocytes. Both myeloid and lymphoid leukaemic cells expressed significant 20 alpha-SDH activity. In addition our data in U-937 and CM-S human cell lines indicate that cells belonging to the myelomonocytic precursor compartment constitutively expressed 20 alpha-SDH activity. Furthermore, this activity was less expressed when these cells were induced to monocyte-macrophage differentiation. In conclusion, our data in the human system indicate that 20 alpha-SDH should not be viewed as a lymphoid lineage-restricted marker enzyme.

T3 expression by human thymocytes in culture

By panning procedures employing T6 and T3 monoclonal antibody, human thymocytes were fractionated into two subpopulations depleted of T6- or T3-positive (T6+, T3+) cells. Unfractionated thymocytes and T6- and T3-depleted subpopulations were separately cultured for 48 h in RPMI 1640 medium with 10% FCS or in HB 101 serum-free medium. Determining the phenotype of unfractionated thymocytes at various time intervals, a time-dependent increase of T3+ cells was observed. An inverse relationship was found between the percentage of T3+ cells and the T6 and peanut agglutinin (PNA) reactive thymocytes. When the surface antigen expression in the T3-depleted population (greater than 95% T6+ and PNA+ cells) was analysed, a strong increase of T3+ cells and a complementary reduction of T6+ and PNA+ cells was evidenced. During that time the surface phenotype of the T6-depleted population (greater than 80% T3+ cells) showed the same trend of differentiation, as the other thymocyte preparations. These results indicate that a conspicuous fraction of human thymocytes and particularly of those characterized by a cortical phenotype (PNA+ and T6+ cells), are able to express mature T-cell antigens when cultured in vitro in the absence of the thymic microenvironment influence. However, the in vitro acquisition of a mature phenotype is not accompanied by a parallel achievement of the capacity to respond to mitogens such as PHA or T3 monoclonal antibody.

Ultrastructural analysis of peripheral blood mononuclear cells in renal allograft recipients

Renal transplanted patients receiving immunosuppressive therapy with glucocorticoids (GC) and azathioprine show in the peripheral blood numerous large mononuclear cells. The origin and the lineage of these cells was not clearly established. In the present study we investigated the surface phenotype and the ultrastructural characteristics of this subset constituted by large mononuclear cells. From peripheral blood mononuclear cells (PBL) of allograft recipients, a cell preparation exhaustively depleted of the relatively numerous monocytes was obtained. At ultrastructural examination two main cellular populations were distinguished: the predominant one (congruent to 85%) was constituted by cells with lymphoid morphology while the other (congruent to 15%) showed myeloid appearance. The large lymphoid cells, T4 or T8 positive, did not express Ia molecules on the surface and were morphologically suggestive of cells in an intermediate stage of the cell cycle between resting and activated lymphocytes. The myeloid population was constituted by promyelocytes, myelocytes and metamyelocytes. Promyelocytes and myelocytes capable of cell division are responsible for the increase of 3H-thymidine incorporation observed in transplanted patient PBL. In conclusion our data suggest that in allograft recipients the immunosuppressive therapy with GC and azathioprine may inhibit the lymphocyte blast transformation and can influence the release of immature myeloid cells responsible for the PBL increased 3H-thymidine incorporation.

Transient deficiency of peripheral blood accessory cells in supporting T cell mitogenesis in patients suffering from chronic idiopathic thrombocytopenic purpura after intravenous gammaglobulin treatment

Mitogenic response of blood lymphocytes to phytohemagglutinin (PHA) and to OKT3 monoclonal antibodies was investigated in 7 patients suffering from chronic idiopathic thrombocytopenic purpura (ITP) before, during and after high-dose intravenous (i.v.) immunogammaglobulin (IgG) infusion. The platelet count rose above the pre-treatment values during infusion therapy in all patients but one. Five out of seven patients presented elevated platelet-associated IgG (PA-IgG) levels at the time of the first infusion; four of these showed an increase in platelet count and a transient reduction or normalization of PA-IgG after IgG infusion. Five out of seven patients showed an impairment of T lymphocyte mitogenic response to PHA and OKT3 before therapy. All patients responded to IgG therapy with a transient deficiency of FcR mediated monocytes (Mo) in supporting T cell mitogenesis induced by both mitogens during and after IgG infusion. This reduced cooperative capability of Mo disappeared at various times after the end of therapy (range 3-12 days). The transient alteration of Mo function, possibly due to a modification in the surface number or in the affinity of Fc-receptors, can explain in part, the increase in platelet count during and after IgSRK infusion.

Effect of glucocorticoids on the development of suppressive activity in human lymphocyte response to a polysaccharide purified from Candida albicans

The action of glucocorticoids on the proliferative response of human lymphocytes stimulated in vitro by MPPS has been investigated. The effect of Dex was dependent on the time of steroid addition to the cultures. Dex added at the beginning of the culture period inhibited, cell proliferation and IL 1/IL 2 synthesis, although not completely. However, a delayed addition of 24 to 48 hr resulted in an enhancing effect on cell proliferative responses that was maximal at day 4. The effect of Dex on T suppressor cell activity was then investigated. Dex added 1 day before the appearance of suppressor cells resulted in a marked decrease or disappearance of the suppressive activity. Moreover, primed T lymphocytes treated with Dex in the presence of exogenous IL 2 enhanced the proliferative responses of fresh autologous PBMC stimulated by MPPS. Taken together, our data suggest that glucocorticoids inhibit the differentiation of T suppressor cells and that IL 2 is unable to reverse this inhibitory effect.

Proliferative capabilities of T3-positive thymocytes

The proliferative responses to phytohemagglutinin (PHA) and to OKT3 monoclonal antibody of various human thymocyte subsets were studied. Unfractionated thymocytes are very poorly responsive cells, as assessed by both PHA and OKT3 stimulation. The mitogen responsiveness is confined to the T3-enriched (T3+) subset, the T6-positive (T6+) cells being almost completely devoid of proliferative capacity. The addition of exogenous IL-2 increases the proliferative responses to PHA and OKT3 of both unfractionated and T3+ thymocytes. This implies that the endogenous IL-2 production by thymocytes is inadequate to fully support the intrinsic proliferative capacity of these cells. Even in the presence of an optimal amount of IL-2, T3+ thymocytes exhibit proliferative responses of lower magnitude as compared to those of peripheral T counterpart (PBT). These observations indicate that the maturative level attained by the T3+ subpopulation within the thymus is considerably inferior to that of T3+ fully immunocompetent peripheral T lymphocytes. Macrophages are activated to produce IL-1 following the stimulation by OKT3-pulsed T lymphocytes. T3+ thymocytes are markedly less efficient than PBT in inducing IL-1 secretion. These data suggest that T3+ lymphocytes within the thymus are relatively immature in terms of cooperative capacities with accessory cells. In conclusion, T3+ cells constituting the more mature intrathymic pool do not reach a complete functional differentiation as compared with the T3+ peripheral counterpart.

Effect of glucocorticoids on the development of suppressive activity in human lymphocyte response to a polysaccharide purified from Candida albicans

The action of glucocorticoids on the proliferative response of human lymphocytes stimulated in vitro by MPPS has been investigated. The effect of Dex was dependent on the time of steroid addition to the cultures. Dex added at the beginning of the culture period inhibited, cell proliferation and IL 1/IL 2 synthesis, although not completely. However, a delayed addition of 24 to 48 hr resulted in an enhancing effect on cell proliferative responses that was maximal at day 4. The effect of Dex on T suppressor cell activity was then investigated. Dex added 1 day before the appearance of suppressor cells resulted in a marked decrease or disappearance of the suppressive activity. Moreover, primed T lymphocytes treated with Dex in the presence of exogenous IL 2 enhanced the proliferative responses of fresh autologous PBMC stimulated by MPPS. Taken together, our data suggest that glucocorticoids inhibit the differentiation of T suppressor cells and that IL 2 is unable to reverse this inhibitory effect.

Interleukin-1 production by a cloned line of human monocyte-like cells (CM-SM). Correlation with state of differentiation

Interleukin-1 (IL-1) production by the human monocyte-like cloned cell line CM-SM has been investigated as a function of the state of cell differentiation. CM-SM cells were induced to differentiate along the monocyte-macrophage lineage by bacterial lipopolysaccharides (LPS) or by 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Cell differentiation was studied by various morphological, functional, cytochemical, and immunological variables, whereas IL-1 activity in the supernatants was measured by the lectin-primed thymocyte proliferation assay. Unstimulated CM-SM cells constitutively produced small amounts of IL-1, and most of the cells appeared relatively undifferentiated. LPS induced cell differentiation, but the effect was reversible, and the cells, in general, did not acquire a capacity for phagocytosis. IL-1 levels were increased about 10-fold over the controls. TPA induced further cell differentiation to macrophage-like cells capable of phagocytosis. IL-1 activity could not be measured directly in the supernatants owing to the synergistic effect of TPA in the assay system. Unequivocal removal of the phorbol was not achieved, but the data indicated that the 'real' levels of IL-1 in the TPA-induced cultures were not significantly higher than those from LPS-induced cultures.

Ia- and IgG-Fc receptor-positive accessory cell sustains peripheral T lymphocyte but not thymocyte mitogenesis induced by OKT3 monoclonal antibody

The proliferative responses of human peripheral blood mononuclear cells (PBL) and thymocytes to OKT3 monoclonal antibody have been investigated. The PBL response to OKT3 was maximal after 72 hr while that of thymocytes was inappreciable at all times measured. Unlike phytohemagglutinin, OKT3 was unable to elicit the mitogenesis of adherent cell-depleted T cells in spite of the presence of exogenously added Interleukin 1 and/or Interleukin 2. The addition of autologous or heterologous adherent cells restored the OKT3 mitogenic response of peripheral purified T cells but not of thymocyte cultures. The adherent cell population that was able to sustain the OKT3-elicited T-cell mitogenesis was constituted by Ia-, Fc receptor-positive cells. These data suggest that the adherent cell-T cell interaction is mediated via the Fc portion of the OKT3 molecule. Furthermore, unlike peripheral T cells, T3-positive thymocytes, which represent the more mature. PHA-responsive subset within the thymus, are unable to cooperate with accessory cells when pulsed with OKT3 monoclonal antibody.

Glucocorticoid inhibitory action on the response to PHA of residual circulatory lymphocytes in renal transplant patients following immunosuppressive therapy

The inhibitory effect of glucocorticoids on the in vitro response to phytohaemagglutinin of the residual circulating T lymphocytes in renal transplant patients during maintenance immunosuppressive therapy with glucocorticosteroids and azathioprine has been investigated. As in normal subjects, the steroid-induced inhibition of transplanted patients' lymphocyte response was inversely correlated with the mitogen concentration used. On the other hand, the response of the various lymphocyte preparations from transplanted patients appeared less inhibited by steroids than the corresponding preparations from normal subjects. The addition to the culture of the adherent cell product interleukin 1 was effective in removing to a similar extent the steroid inhibitory effect on lymphocytes from normal and transplanted subjects. Thus, the lesser inhibitory effect of glucocorticoids on transplanted patient lymphocytes could be explained by the higher percentages of monocytes present in all peripheral blood mononuclear cell preparations. These results suggest that during immunosuppressive therapy with glucocorticoids and azathioprine the residual circulating lymphocytes have a responsiveness to in vitro dexamethasone suppression similar to that of normal peripheral blood lymphocytes.

Dissociation between coupled lymphocyte phenotypic and functional properties in Sézary cells

Neoplastic lymphocytes derived from three patients suffering from Sézary syndrome were studied by immunologic and functional analysis. Populations of neoplastic T cells (greater than 90% as judged by morphologic criteria) were isolated from involved lymph nodes. Sézary cells expressed T3 and T4 but not T8 membrane antigens displaying the same phenotypic pattern of normal helper/inducer T cells. On the contrary the mitogenic response of Sézary cells to phytohemagglutinin appears lower than that exhibited by peripheral T lymphocytes. The amounts of interleukin 2 produced by Sézary cells were examined in two out of three cases: in one case it appeared similar to that produced by peripheral blood lymphocytes while in the other it was about one-half lower. Furthermore the capacity of dexamethasone at 10(-7) M in inhibiting T-cell mitogenesis was comparatively analyzed in T lymphocytes from Sézary lymph nodes, reactive lymph nodes, normal peripheral blood, and normal thymus. It was clearly apparent that the mitogenesis of Sézary cells, unlike that of peripheral blood lymphocytes and that of lymphocytes from reactive lymph nodes, was strongly inhibited by dexamethasone (greater than 70%); such inhibition was very similar to that observed for normal thymocytes. Taken together these results suggest that despite the phenotypic pattern of mature helper/inducer T cells, Sézary lymphocytes are functionally a less mature T-cell type.

Glucocorticoid receptors and cortico-sensitivity in a human clonal monocytic cell line, CM-SM

CM-SM is a clonal line of human precursor mononuclear phagocytes inducible to macrophage differentiation in response to the tumor promoter phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Untreated CM-SM cells contain single class, high-affinity (KD = 4.0 X 10(-9) M) glucocorticoid-specific receptor sites (approximately 60,000 per cell), as measured by a whole cell assay, at 37 degrees C, using [3H]triamcinolone acetonide (TA). Exposure of CM-SM to dexamethasone (DEX) produced a progressive, dose- and time-related series of changes in CM-SM cell growth, saturation density, morphology, and functional properties, with half-maximal effects at about 10(-9) M for DEX. TA-receptor sites rapidly decreased (about 70%) after DEX treatment, without any apparent change in steroid specificity and affinity. After 5 days in culture with a saturating concentration (3.6 X 10(-8) M) of hormone, the cells reached a saturation density of about 9.0 X 10(6) viable cells/ml (about 4.0 X 10(6) viable cells/ml in the controls), while the modal volume of the resulting cell population was approximately 60%, as compared to the volume of untreated cells. DEX-treated cells appeared less differentiated than controls, as assessed by combined morphologic, antigenic, and cytoenzymatic analyses. DEX almost completely inhibited TPA activation of the following macrophage functions: adherency to the culture plate, expression of lysosomal enzymes, Fc and C3 receptors, and stimulation of phagocytosis. After removal of DEX, the cells, within a few passages, returned to a state apparently identical to the untreated controls and could be induced to macrophage differentiation in response to TPA.

A human thymoma with prothymocyte-like infiltration

We have examined a human thymoma, round-oval epithelial-type cell with moderate lymphocytic infiltration, whose major lymphocytic component (67%), unlike the minor one (33%), did not form rosettes with sheep red blood cells (E rosettes). However, these cells were of T-cell nature as indicated by the positive staining for both acid phosphatase and beta-glucuronidase, two well-accepted cytochemical markers for T cells. The non-E-rosetting lymphocytes expressed T 10, but not T 3 and T 6 antigens. Moreover, they lacked both peanut agglutinin and Fc-IgG receptors. On the contrary, 71 and 19% of the E-rosetting cells were PNA- and Fc-IgM-receptor positive, respectively. Furthermore, the non-E-rosetting cells were phytohemagglutinin unresponsive. The non-E-rosetting lymphocytes were larger (greater than 7 micron) than the E-rosetting cells and showed a different nuclear chromatin pattern. These immunological, cytochemical, and morphological features strikingly resemble those exhibited by cells (prothymocytes) normally found only in fetal thymus. On the basis of these findings we hypothesize the existence in this thymoma of a prothymocyte-like infiltration.

Human thymoma lymphocyte mitogenesis: glucocorticoid inhibitory capacity as a function of the size of the more mature T cell subset

The relationship between the expression of T3 and T6 antigens and the capacity to respond to phytohaemagglutinin (PHA) has been studied in the lymphocyte component of nine human thymomas. It appears that there is a positive correlation between the mitogen responsiveness of thymoma lymphocytes and the relative proportion of T3 positive (T3+), T6 negative (T6-), peanut receptor negative and IgM-Fc receptor positive cells. Moreover we have comparatively investigated the dexamethasone (Dex) inhibitory effect on the mitogenesis of T lymphocytes from thymoma, normal thymus and peripheral blood. In the presence of the macrophage product interleukin 1, the capacity of Dex to inhibit the mitogenesis of peripheral blood purified T cells (PBT) is inversely correlated with the PHA concentration used. Conversely, Dex completely (greater than 90%) inhibits thymocyte mitogenesis irrespective of PHA concentration. The entity of Dex inhibitory effect on thymoma lymphocyte mitogenesis shows a great variability ranging between that observed in normal thymocytes and that observed in PBT. In each thymoma case the degree of inhibition appears to be dependent on the size of the more mature thymocyte pool being positively correlated with the number of T6+ but negatively with that of T3+ cells. Our data demonstrate a high degree of variability among thymomas relative to the phenotypic and functional properties of their lymphocytic component. On the other hand, in some thymomas the phenotypic and functional characteristics of lymphocyte component seem to represent only a narrow span of normal thymocyte maturative pathway. In this respect, human thymoma may constitute a profitable tool for studying the intrathymic T lymphocyte maturative steps.

Constitutive production of Interleukin-1 by the human continuous cell line, CM-S

Supernatants from the human continuous cell line, CM-S, have been tested for Interleukin-1 (IL-1) activity and found to constitutively elaborate this factor. The CM-S-produced IL-1 activity has been partially purified and shown to be similar to IL-1 produced by human and mouse peripheral blood macrophages. To the best of our knowledge this is the first continuous human cell line reported that produces this monokine.

Modulation of glucocorticoid inhibitory action on human lymphocyte mitogenesis: dependence on mitogen concentration and T-cell maturity

The inhibitory effect of glucocorticoids on the mitogenesis of human T cells derived from thymus and peripheral blood compartments have been investigated. The capacity of dexamethasone (Dex) (10(-7) M) of inhibiting the peripheral blood lymphocyte (PBL) mitogenesis was inversely correlated with the phytohemagglutinin (PHA) concentration used. Conversely, Dex completely (greater than 90%) inhibited the thymocyte mitogenesis, irrespective of PHA concentrations. T cells purified from PBL (M phi less than or equal to 1%) behaved as thymocytes regarding the Dex inhibitory pattern. The addition of macrophages (M phi) or interleukin 1 (IL1) was effective in removing the Dex inhibitory effect on T cells purified from PBL, but not on thymocytes. The higher corticosensitivity of thymocyte mitogenesis in comparison to PBL mitogenesis cannot be explained by differences in the relative number of M phi, but seems an intrinsic property of these less mature T cells.

Functional properties of human thymoma lymphocytes: role of subcellular factors in blastic activation

The proliferative responses to phytohemagglutinin and the role of subcellular factors in the modulation of blastogenesis of thymoma lymphocytes from 5 thymoma patients were investigated. The addition of exogenous interleukin 1, a macrophage product, strongly augmented the blastic transformation of cultured thymocytes from both normal and neoplastic glands by influencing the production of interleukin 2 (IL-2) by a well-defined T-cell subset. The magnitudes of the blastic responses were ultimately modulated by the amount of IL-2 released in culture. The higher proliferative responses exhibited by thymocytes from thymoma were effectively sustained by a higher production of IL-2 in culture. In addition to having distinctive surface membrane receptors in common with normal thymocytes, thymoma lymphocytes were also under the influence of the same subcellular factors involved in T-cell blastic activation as thymocytes. These observations imply the presence of functionally distinct subpopulations in the thymoma lymphocyte component and add arguments in favor of their nonneoplastic nature.

Imbalances in peripheral blood T-cell subpopulations in renal transplant patients

The distribution of T-lymphocyte subpopulations bearing receptors for the Fc portion of IgG (TG) or IgM (TM) was monitored in 22 renal allograft recipients treated with immunosuppressive therapy and in 10 uraemic patients on haemodialysis. No significant difference in the distribution of T cells and T-cell subsets was found between normal controls and haemodialysed patients. In transplanted patients, however, a significant reduction of the total T-cell percentage (P less than 0.005), of TM subset percentage (P less than 0.025) and absolute number (P less than 0.005) and of TG absolute number (P less than 0.05) was observed. Considering patients with allografts functioning for more than 1 year only, the reduction in TM cells in terms of percentage (P less than 0.0005) and absolute number (P less than 0.025) was significant, while TG subset levels did not change significantly. In patients transplanted less than 1 year previous to our study, total T cells and T-cell subsets were reduced significantly only as absolute numbers. During the 1st year we observed several increments of TM values towards normal levels, especially in the first 2 months after transplantation. During this period, TM subset levels sharply increased at acute rejection crisis and returned to previous values with rejection reversal. Our results suggest that the TM subset plays a prominent role in the mechanisms involved in the immunological response to allografts, and therefore repeated TM cell monitoring could be useful in the follow-up of renal transplant patients.

Pseudolymphoma of the lung: lymphoid subsets in the lung mass and in peripheral blood

Studies of the lymphocyte markers in a case of pseudolymphoma of the lung indicate a non-neoplastic nature of the lymphoid infiltrate. The relative proportions of T and B cells and of the markers for the various subsets of both populations reflect the morphologically mixed character of the cellular infiltrate of the lung mass. Moreover, an imbalance of T cell subsets was observed in the peripheral blood: the numbers of T cells with receptors for IgM (TM) were persistently decreased while an increase of the values of T lymphocytes with receptors for IgG (TG) was noted. In addition an altered immunologic status of the patient was indicated by the in vivo impairment of cellular immunity as demonstrated by the failure to respond to common antigens and to become sensitized to 1-chloro-2,4-dinitrobenzene (DNBC).

Human thymoma: immunologic characteristics of the lymphocytic component

Several immunologic parameters were investigated in the lymphocytic component of ten thymomas, characterized by a variable degree of lymphocytic infiltration. The majority of thymoma lymphocytes are T-cell in nature, as are lymphocytes from the normal thymus. Lymphocytes from six thymomas with moderate or predominant lymphocytic infiltrates were capable of forming stable E-rosettes, (mean percentage +/- SD: 78.0 +/- 5.2); binding peanut agglutinin (67.3 +/- 8.6); and exhibiting receptors for the Fc-portion of IgM (21.8 +/- 6.0) at percentages that were close to those found in the normal thymus. On the other hand, lower numbers of stable E-rosetting cells (26.8 +/- 8.7), PNA-positive cells (27.5 +/- 12.4), and remarkably higher percentages of cells with receptors for IgM (54.0 +/- 4.2) were demonstrated by the lymphocytic population of four thymomas with scant lymphocyte components. In addition, lymphocytes from tumors with scant lymphocyte components show a higher proliferative response to phytomitogen (PHA), therefore exhibiting immunologic features comparable to those of the more mature pool of normal medullary thymocytes. The observed immunologic similarities between the populations of lymphocytes from thymomas and from the normal thymus gland suggest an exclusively epithelial origin of the thymoma.

Glucocorticoid receptors and in vitro corticosensitivity of peanut-positive and peanut-negative human thymocyte subpopulations

In 6 human thymus glands, the immature subset of thymocytes was separated from the more mature one, by differential peanut lectin agglutination. These 2 cell subpopulations were analyzed for glucocorticoid receptor content by using a whole cell assay, with (3H)-triamcinolone acetonide as tracer. The unagglutinated thymocytes (peanut negative) contained about 2 times more receptor sites per cell than agglutinated (peanut positive) ones (7650 +/- 1550 S.D. verus 3195 +/- 896 S.D.). The affinity for steroid was similar in both cell subsets, as was the stereospecificity for glucocorticoids, the time-course of steroid-receptor association, and cytoplasmic to nuclear translocation. Despite the greater number of glucocorticoid receptor sites, the peanut-negative thymocyte subpopulation did not differ from the peanut-positive one in its sensitivity to the inhibitory effects of triamcinolone acetonide, as determined by measurements of the incorporation of radiolabeled precursors of protein and DNA. Moreover, the peanut-negative subset appeared more resistant in vitro to the steroid-induced cell lysis as compared to the peanut-positive one. Thus, our data suggest that glucocorticoid receptor density and corticosensitivity are not directly correlated and that the number of glucocorticoid receptor sites may be dependent on the degree of immunologic maturation.

Glucocorticoid receptors and in vitro corticosensitivity of peanut-positive and peanut-negative human thymocyte subpopulations

In 6 human thymus glands, the immature subset of thymocytes was separated from the more mature one, by differential peanut lectin agglutination. These 2 cell subpopulations were analyzed for glucocorticoid receptor content by using a whole cell assay, with (3H)-triamcinolone acetonide as tracer. The unagglutinated thymocytes (peanut negative) contained about 2 times more receptor sites per cell than agglutinated (peanut positive) ones (7650 +/- 1550 S.D. verus 3195 +/- 896 S.D.). The affinity for steroid was similar in both cell subsets, as was the stereospecificity for glucocorticoids, the time-course of steroid-receptor association, and cytoplasmic to nuclear translocation. Despite the greater number of glucocorticoid receptor sites, the peanut-negative thymocyte subpopulation did not differ from the peanut-positive one in its sensitivity to the inhibitory effects of triamcinolone acetonide, as determined by measurements of the incorporation of radiolabeled precursors of protein and DNA. Moreover, the peanut-negative subset appeared more resistant in vitro to the steroid-induced cell lysis as compared to the peanut-positive one. Thus, our data suggest that glucocorticoid receptor density and corticosensitivity are not directly correlated and that the number of glucocorticoid receptor sites may be dependent on the degree of immunologic maturation.

Lymphocyte subsets in human thymus: expression of IgM-Fc receptor by peanut agglutinin positive and negative thymocytes

The number of cells bearing receptors for the Fc portion of IgM (TM) and IgG (TG) has been evaluated in the human thymus. After overnight incubation the TM cells were 26.2 +/- 2.1% (mean +/- SE) in unfractionated thymus cell suspension, 23.4 +/- 3.8% in peanut agglutinin positive (PNA+) and 32.6 +/- 3.2% in PNA-negative (PNA-) fraction. PNA+ and PNA- fractions mainly consist of cortical and medullary thymocytes, respectively. The presence of TG was negligible. The fine structural features of TM cells from the thymus were very similar to those reported for TM lymphocytes from peripheral blood. In short-term culture a time-dependent increase of TM cells was observed. After 96 h of culture more than 60% of the thymocytes were shown to bear the Fc receptor of IgM. At the same time PNA+ and PNA- fractions expressed about 70% and 42% of TM cells respectively. The number of TG remained negligible. Our data indicate that in the human thymus there exists a distinct, quantitatively well-represented TM subset. Most probably, the peripheral TM cells derive from this subset which is present in both the cortex and the medulla of the thymus. Finally, the higher blastic responses to PHA exhibited by TM cells from PNA-subpopulation suggest that the most advanced intrathymic maturative step is attained by this distinct subset.

Lymphocyte subpopulations in non-neoplastic thymus from myasthenia gravis patients

Lymphocyte populations in non-neoplastic thymuses from fifteen patients with myasthenia gravis (MG) were examined. As in normal subjects, the great majority of thymic lymphocytes of MG patients are T cells. When MG thymuses were compared to normal glands, lower percentages of lymphocytes able to form E rosettes resistant to incubation at 37 degrees C (stable E rosettes) were found in MG thymuses. A negligible B cell content was detected in eight normal and in eight MG thymuses with absent or rare lymph follicles; but there was a substantial B cell presence in the thymuses of seven MG cases with thymic hyperplasia containing many germinal centres. Normal and MG thymuses contain the same percentage of lymphocytes bearing receptors for the Fc portion of IgM (TM). Moreover, the IgM Fc receptor was found mostly on cells which did not form stable E rosettes and did not bear surface immunoglobulin. The possible significance of these findings is discussed.

Subpopulations of lymphocytes in human thymomas

Lymphocyte populations in six normal thymuses and ten thymomas were examined. The majority of lymphocytes from both thymus and thymoma differ from peripheral T lymphocytes in their capacity to form E-rosettes resistant to incubation at 37 degrees C. Low percentages of T lymphocytes bearing receptors for the Fc portion of IgG (TG) and IgM (TM) were found in normal thymus. In contrast, lymphocytes from five out of nine thymomas showed remarkable percentages of TM cells. Compared with normal thymocytes, lymphocytes from seven out of ten thymomas responded vigorously to mitogens. The possible origin and nature of thymoma lymphocytes are discussed.

T-cell nature of leukaemic cells in a case of Sézary's syndrome with 'null-cell' features

alpha-naphthyl acetate esterase (ANAE) activity has been investigated in leukaemic cells from peripheral blood in a typical small-cell Sézary syndrome (SS) case in which cerebriform mononuclear cells failed to form E rosettes. The 'dot-like' ANAE positivity found in the majority of these neoplastic cells strongly supports a T-cell origin. In addition, a non-monocytic, non-B-cell nature of Sézary cells is indicated by the lack of Ia-like antigens. Finally, there is evidence of a distinct portion of Sézary cells simultaneously expressing ANAE activity and Fc IgM receptors.

Subpopulations of T lymphocytes in myasthenia gravis patients

Subpopulations of human peripheral blood T lymphocytes were examined in twenty-three myasthenic patients. T lymphocytes bearing receptors for the Fc portion of IgG (T gamma) were significantly increased in a third of the patients examined. T lymphocytes bearing receptors for the Fc portion of IgM (Tmu) were within normal values in all but two patients. Possible implications of these cells in the pathogenesis of myasthenia gravis are discussed.

Structural and functional characteristics of hairy cells

Morphological, cytochemical, immunological and ultrastructural studies were performed on peripheral blood mononuclear cells from a patient with hairy-cell leukemia. Immunofluorescence studies showed a very strong intensity of fluorescence and indicated that hairy cells had monoclonal surface-membrane immunoglobulins (SmIg) actively produced by the cells. An unusual spontaneous SmIg redistribution induced by antibodies was also noted. Immunoultrastructural studies demonstrated that antibody-induced redistribution of SmIg on hairy cells is in form of a singular polar cap and that the cell membrane is rapidly cleaned of the complexes by endocytosis. The behavior of hairy cells regarding several membrane markers, mitogen stimulation and antibody-induced cytotoxicity suggests that hairy projections could represent the expression of a functional stage common to different lymphocyte subpopulations, or alternatively, a marker of a peculiar subset of B lymphocytes.

Echinococcus granulosus: specific quantification of the two most immunoreactive antigens in hydatid fluids

Preparations of the two most immunoreactive Echinococcus granulosus antigens (antigens 4 and 5) from sheep hydatid fluid, purified by a simplified method, and monospecific antisera against antigens 4 and 5, prepared by a new procedure, were used to measure the antigenic concentrations of antigens 4 and 5 in swine, sheep, and human hydatid fluids from pulmonary or hepatic cysts. Two bovine samples and two commercial preparations were also tested. The concentration of both antigens was significantly higher in sheep and human hydatid fluids than in swine hydatid fluid. The antigenic content of the two bovine samples and of the two commercial preparations was below the sensitivity level of the method employed. Independently of the species tested, the amount of Echinococcus antigens was greater in hepatic than in pulmonary cysts. The ratio between the concentrations of antigens 4 and 5 was constant at about 1:10 in the samples from various organs and from different species. When there were enough samples for statistical analysis a linear correlation was found between the contents of these two antigenic components but there was none between the amounts of proteins and the antigenic concentrations in the single cysts. Sheep hydatid fluid must therefore be considered the best source of antigenic material for diagnostic purposes even though in human cysts the antigenic fraction is less contaminated by serum proteins. We describe a reliable method of standardising antigenic material for the immunodiagnosis of hydatid disease.

Inhibitory activity of alpha-1-antitrypsin bound to human IgA

Complexes between alpha-1-antitrypsin (alpha 1AT) and monoclonal IgA are regularly demonstrable in the plasma of myeloma patients. These alpha 1AT-IgA complexes, free of contamination by unbound alpha 1AT, are purified from 5 myeloma patients sera using salt-mediated hydrophobic chromatography. The complexes have a molecular weight greater than or equal to 400 000: this suggests that alpha 1AT is bound to di- or polymeric IgA. The alpha 1AT bound to IgA constitutes the 3.2, 3.5, 7.2, 8.5, and 24.6 per cent of the total alpha 1AT present in the 5 myeloma serum samples. There is a linear correlation between bound alpha 1AT concentration and IgA level in the range of the IgA concentrations considered (r = 0.988; p less than 0.05). Similar values are obtained quantitating bound alpha 1AT by radioimmunodiffusion technique or by determination of the trypsin-inhibiting capacity; this demonstrates that the bound alpha 1AT fully retains its inhibitory capacity. The biological significant of this binding phenomenon is discussed.

Alpha-1-antitrypsin in umbilical cord serum: pi phenotypes and relationships with idiopathic respiratory distress syndrome

The concentrations and phenotypes of serum alpha-1-antitrypsin (alpha1AT) were determined in 650 newborn infants. The distribution of these 650 subjects among the various Pi phenotypes confirms the higher frequency reported for the PiS allele in Latin populations. Serum alpha1AT levels vary between one phenotype and the other. Besides, at birth, infants weighing more than 2,500 g have alpha1AT levels significantly higher (P less than 0.001) than infants weighing less than 2,500 g; this difference in serum alpha1AT concentrations is due to the low alpha1AT levels found in preterm infants. The significantly lower alpha1AT concentrations found in preterms is associated with a higher risk of developing IRDS and with a mean birth weight under 2,000 g. Infants who develop IRDS frequently have lower alpha1AT levels than those who do not develop the syndrome, independently from body weight. On the basis of serum alpha1AT quantitation, newborn infants may be separated into two groups, characterized respectively by concentrations above or below 150 mg%. From our data, it appears that if the group with an alpha1AT concentration lower than 150 mg% is phenotyped, it is possible to differentiate infants with a high risk of fatal IRDS from individuals with a "pathological" phenotype.

Alpha-1-antitrypsin phenotypes in newborns from Central and Southern Italy

The results of Pi typing on 500 infants from Central and Southern Italy are reported. Phenotype determinations were performed on umbilical cord serum. We observed nine different phenotypes; each of these is present in other European populations. The frequencies of the Pi alleles in our group were found to be, on the whole, comparable to those found in other populations widely separated geographically. However, the frequency of the Pi S gene in our sample (0.0670) was greater than that observed in Northern and Central European and American groups. Our Pi S frequency was similar to that found in a French group and lower than that of Spanish and Portuguese groups. Our data thus confirm the higher Pi S gene frequency in Latin populations.

Echinococcus granulosus: identification of subunits of the major antigens

This paper describes a procedure for obtaining the two "major" Echinococcus granulosa antigens (antigens 4 and 5) from sheep hydatid fluid. Purified antigen 4 (m.w. 400,000 and over) and antigens 5 (m.w. 150,000) were separated in order to identify molecular subunits of each. SDS 12.5% polyacrylamide gel electrophoresis of antigen 4 gave a single band for which a m.w. of 67,000 was calculated. When 5% 2-mercaptoethanol was added to the antigen 4 preparation, SDS 12.5% polyacrylamide gel electrophoresis gave two bands (m.w. 47,000 and 20,000). SDS 12.5% polyacrylamide electrophoresis of antigen 5, with or without 2-mercaptoethanol, gave at least three bands with m.w. ranging from 10,500 to 20,000. Low m.w. subunits of both antigens were eluted in a single peak from a preparatory SDS 7.5% acrylamide gel electrophoresis; these subunits were found to be immunogenic and antigenic.

Isolation of the most immunoreactive antigenes of echinococcus granulosus from sheep hydatid fluid

This paper describes a simplified procedure for obtaining purified Echinococcus granulosus antigens from sheep hydatid fluid by using affinity chromatography on concanavalin A-Sepharose. The presence of two "major" antigens (4 and 5) was confirmed. Antigen 5 was isolated by preparative polyacrylamide gel electrophoresis. Antigen 4, eluted by diffusion from the gel, was seen to be "contaminated" by antigen 5 and was isolated by using anti-5 Sepharose-linked serum. These two major antigens were then tested separately against the sera of hydatidosis patients by using very simple immunolgic tests. The best results were obtained in passive hemagglutination with antigen 4. Antigen 4 is the most immunoreactive parasitic antigen; antibodies against it were found in the sera of all hydatidosis patients showing positive reaction. Apart from the direct use of this antigen in serologic tests, it appears possible to standarize the most frequently used and commerically available antigenic materials by titrating this component.