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Natural measles virus infection is recognized for causing prolonged abnormalities in immune responses, that contribute to the severe and complicated evolution of the disease. Immunization with live measles virus vaccine could be considered a mild form of the measles infection. Results of investigation of in vitro immune response after measles immunization with live attenuate vaccine have been conflicting. In this work we studied cellular immune parameters in children aged between 3 and 12 years. T cells, CD4+ and CD8+ subsets were analyzed by cytometry. CD3+ cells were significantly reduced compared to controls (p < 0.01) whereas CD4+/CD8+ ratio was normal. The in vitro proliferative response to polyclonal mitogen was significantly reduced (p < 0.01). This study confirms the presence of a mainly functional immunosuppression of cellular response in a cohort of children belonging to a developed area. These findings improve the understanding of the mechanism of immune response to virus measles and provide suggestions for the development of a better approach to immunization, taking account for the strain, vaccine titre, age and environmental conditions of the target population.

As reproducible models for examining human early B-cell progenitors (BCPs) are poorly developed, the cells and molecules regulating their growth and differentiation are still incompletely characterized. We used a recently published short term culture system, using immunomagnetic beads and negative selection, in order to isolate an early BCPs enriched population from human fetal tissues that support further studies on B cell proliferation or differentiation events. This purified population was incubated with or without human recombinant Interleukin-4 (rIL4), and its capability to proliferate and differentiate was followed. We found that rIL4 did not induce either proliferation or differentiation of purified human BCPs. Furthermore in the presence of stromal cells (CD13+) it was able to enhance cy mu + cells and to induce the expression of surface Ig (sIg), surface CD22 on in vitro TdT + CD19 + CD10 + sIg-fetal liver cells. Human recombinant interleukin-7 (rIL-7) promoted the proliferation and the clonal growth of Tdt + CD19 + CD10 + fetal BCPs, confirming its critical role at early stages of human B lymphopoiesis. Furthermore rIL7 also induced growth of CFU-GM when unseparated fetal tissues or myeloid/monocytic contaminated BCPs were used as a target populations, probably by indirect mechanism. Transforming growth factor -beta (TGF-beta 1) partially inhibited the stromal cell-dependent rIL4 induced differentiation and rIL7 clonal growth and proliferation of fetal BCPs. Our study contributes to elucidate the growth factor requirements that characterize normal human B-cell ontogeny, suggesting another mechanism for the linkage between lymphopoiesis and myeloid/macrophagic micro-environment. The in vivo implications of this study are discussed.

The impairment of humoral immunity with rapid turn-over of cellular B clones in children with HIV infection is known as well as the conduct of LDH isoenzymes in B cell lymphoproliferative diseases like Burkitt's lymphoma. Therefore, serum lactate-dehydrogenase activity (LD, EC 1.1.1.27) and its isoenzymes have been evaluated twice (within 12 months) in 11 children with HIV infection with respect to a control group (30 subjects). Furthermore, the relationship between those and other clinical and immunologic parameters (total lymphocytes, CD4/CD8, immunoglobulins, classification according to the Atlanta CDC 1987) has been studied. HIV infected children have shown a significant decrease in LD1 rates, which was directly correlated to CD4/CD8 values. After the follow-up, this correlation became even more significant. Thus, these findings may suggest the usefulness of LDH isoenzymes evaluation as a marker of disease activity in children with HIV infection.

Conditioned medium from a T-lymphoblastic cell line (Mo) is known to produce factors promoting CFU-GM, BFU-E and CFU-MK. In our study we investigated the potential CSA of conditioned media obtained from Mo and its subclone J on normal and malignant lymphoid progenitors of both T and B lineage. Both cell lines release factors inducing a significant increase in number and size of T-lymphoid colonies when compared to standard source of factors (PHA-LCM). On the contrary, they presented a low CSA on B cell precursors confirming the difficulties in identifying a source of growth and differentiation factors for human B cell ontogeny. This study contributes to the knowledege of biological properties of these tumor cell lines, suggesting the possibility to employ Mo- and J-derived supernatants in vitro for improving growth potential of normal and malignant T cell progenitors.

The recognition and identification of subtle chromosomal changes in leukemic cells has greatly been facilitated since the advent of high-resolution banding techniques. However efficient utilization of these methods is often hampered by the paucity of leukemic cells during clinical remission, the variability of cell cycle length and tissue culture conditions. Therefore the detection of minimal residual disease in acute lymphoblastic leukemia by cytogenetic methods requires a preselection of material to be examined. In this preliminary report analyzable metaphases could be obtained in cultured cells from a colony assay for malignant peripheral B cell progenitors, whereas in marrow samples direct or 24 hours G-banding technique had failed to reveal metaphases in common Acute Lymphoblastic Leukemia patients during complete remission. It is believed that in common Acute lymphoblastic Leukemia patients this B cell colony assay permits the clonal expansion of residual circulating cells linked to malignant clone that are not detectable by classic hematologic and cytologic methods. In addition, this culture procedure substantially improves the sensibility of cytogenetic approach to the study of minimal residual disease in acute lymphoblastic leukemia during complete remission.

It is generally agreed that HIV itself has the primary role in the initiation and propagation of the pathogenic process of the infection. Nonetheless, a number of important issues concerning the pathogenesis of HIV infection remain unresolved. For example, it remains unclear how CD4+ T cells are lost after HIV infection. The low frequency of infected cells seen even in advanced infection implies that a direct cythopathic effect of HIV on infected CD4+ T cells cannot explain their disappearance. Multiple and diverse mechanisms have been proposed as supplements to the HIV in the destruction of CD4+ cells and the pathogenesis of AIDS. However, it is not yet possible to state confidently which additional mechanism(s) is important. Identification of the nature of this supplemental process has become essential for successful, non-harmful intervention. We propose here a short analytical review of the possible supplemental mechanisms of immunological destruction in AIDS in order to emphasize the complexity of the pathogenesis of the disease.

Background: Sensitive methods for detecting residual disease may complement conventional morphology while monitoring the response to treatment in leukemia patients., Methods: We studied minimal residual disease (MRD) by selecting via a colony assay a peripheral blood (PB) cell population enriched in putative malignant cells and detecting occult leukemic cells by double immunologic analysis performed on colonyforming cells (CFC). Using this combined technique we assayed the PB of high risk children with acute lymphoblastic leukemia (ALL) in order to demonstrate possible differences in "the residual tumor cell burden" among leukemia patients and to correlate these with a 3-year clinical follow-up., Results: In all 22 patients positive results were obtained for up to 18 months following induction chemotherapy at times of apparent hematologic remission. Common ALL (cALL) patients exhibited a mean of 9.6% cAlla+ cells (range: 2% to 30%), whereas cALL antigen (cALLA) and cALLA/Tdt or CD1a/Tdt combination were never found in the colonies derived from healthy individuals. Six out of 22 cALL patients expressed a mean of 16.5% cALLA+/Tdt+ CFC (range: 2% to 35%). Five T-ALL children presented a mean of 24% CD1a/Tdt+ cells (range: 8% to 44%). Extensive follow-up indicates a correlation between the percentage of CFC Tdt+/lymphoid marker+ cells (more than 10%) and subsequent clinical relapse. In one patient relapse occurred after 16 months with a dramatic increase in the number of leukemic cells. In contrast, the decline in malignant cells, observed in two cases, predicted a favourable course. Five patients tested before autologous bone marrow transplantation (ABMT) presented high number of positive cells and relapsed at various times., Conclusions: We conclude that this approach to the study of MRD could be valuable in monitoring the efficacy of chemotherapy, as well in evaluating the quality of purged marrow.

Considering that in the HIV infection there is a precocious deterioration of humoral immunity with rapid turn-over of cellular B clones, we have evaluated the conduct of serum lactate-dehydrogenase activity (LD, EC 1.1.1.27) and its isoenzymes in 21 children born from HIV-positive mother respect to a control group (30 subjects). Furthermore we have checked the existence of a probable correlation between those and other clinical and immunologic parameters (total lymphocytes, CD4/CD8, immunoglobulins, classification according to the Atlanta CDC). In seropositive children we saw, respect to those evolved towards P3 stage, a significantly raising of LD4 (also vs. control group) for likely pulmonary parenchyma's damage, LD3 for B immature lymphocytes' increase and a reduction of LD1 (also vs. control group) for mature clones' decrement. Furthermore in seropositive subjects there was the existence of a direct correlation between LD1 and CD4/CD8 values. As such, the evaluation of LD isoenzymes can establish an useful element in the clinical monitoring of seropositive children.

Stromal cells appear to be key regulatory elements in hematopoiesis and lymphopoiesis. Several stromal cell lines can support B lineage by creating a hematopoietic microenvironment via cell contact or regulatory humoral molecules. These activities have been efficiently mediated by an adipocytic stromal cell line 14F1.1 on infant leukemia cells expressing a hybrid pre-B myeloid phenotype. Several murine cell clones, however, are known to have different ability to support growth and/or differentiation of leukemic cells depending on the maturational stage in which malignant cells are frozen. Pre-B-cell lines and fresh leukemias were therefore cultivated on S17 stromal cell line, before and after exposure to human recombinant interleukin 4 (rIL4), a cytokine whose effects on the growth and differentiation of the B-cell compartment depend on the developmental stage of the target B cell. In the present work, leukemic cells, both in suspension and in close contact with stromal cells, maintained their original phenotype throughout the whole period of co-culture with S17, either before or after exposure to human rIL4.

Experimental models, clinical and histopathological observations suggest a thymic origin of childhood T acute lymphoblastic leukemia (T-ALL). We studied thymic epithelial function in childhood T-ALL as compared to normal controls in order to improve our understanding of the cellular immunodeficiency mechanisms operating in a thymus-linked malignant process. The levels of Facteur Thymique Sérique (FTS) were measured in 9 patients at diagnosis, according to the rosette inhibition assay of Dardenne & Bach (1975). This method is based on the capacity of human serum containing FTS activity to confer on rosette-forming cells (RFC) from adult thymectomized mice a sensitivity to azathioprine identical to that of normal mouse RFC. All patients presented low age-corrected titres of FTS. No zinc deficiency was found, suggesting that low FTS levels are not related to unexpressed FTS biological activity. Plasma from all the children studied contained factors capable of inhibiting the biological activity of FTS in vitro. However, the nature of this inhibitor has not yet been elucidated. Our study shows the presence of a thymic dysfunction in childhood T-ALL, which could partially explain the immunodeficiency described in these patients. The linkage of the leukemic process with a primitive thymic involvement is discussed.

An in vitro B-cell colony assay system was used to evaluate B-cell differentiation from peripheral blood precursors in common acute lymphoblastic leukemia (cALL) patients in remission as compared to normal controls. Significant differences in the morphologic and phenotypic features of pooled colony cells were found between the two groups. The morphology and surface markers of control-cultured cells were those of young plasmocytes. In contrast, patients' cells had predominantly a lymphoblastoid appearance and a mean of 18% (2-72%) of the cells expressed the cALL (CALLA) antigen. This marker, known to be present on normal pre-B-cells and malignant cALL cells, was not found on control colony cells. Cytogenetic studies performed in four cases showed that a fraction of the patients' colony cells had karyotypic abnormalities similar to that of the original lymphoblasts. These data suggest that the cells with immature features persisting in the colonies of cALL patients are the progeny of residual circulating cells linked to the malignant clone which cannot be detected in the fresh sample and are clonally expanded during the culture.

In some patients with histiocytosis-X there is a deficiency of suppressor T cells, which is corrected in vitro by incubation with either crude calf thymic extract or thymostimulin. This finding suggests that a thymus deficiency could be involved in this disease. Low levels of serum thymic factor (FTS) are found in patients with histiocytosis-X. Their plasma contain factors capable of inhibiting biological activity of FTS in vitro. Elucidation of the mechanism by which FTS is inhibited would be helpful in understanding the immunological defect in histiocytosis-X. The presence of evidence of thymic dysfunction and the fact that patients respond to thymic hormone therapy suggest that histiocytosis-X could be due to a primary immunodeficiency syndrome. Thymulin, which stimulates the generation of suppressor T cells, could be of benefit in therapy.

We measured serum levels of Facteur Thymique Sérique (FTS) in 56 young cancer patients compared to normal controls. All patients who received immunosuppressive therapy had low age-corrected titres of FTS. Low levels were also found at diagnosis and off therapy. Plasma from 22 patients contained factors capable of inhibiting biological activity of FTS in vitro. The nature of this inhibitor has not been elucidated. No zinc deficiency was found in the patients studied, suggesting that FTS is secreted in its active form. Our study points out the importance of monitoring FTS activity in young cancer patients for its implications on immunological surveillance. The practical applications of thymic hormone therapy in cancer patients are discussed.

Two series of normal and leukaemic lymphocytes were examined by infrared spectroscopy in order to try to find spectral differences connected with chemical and biological modifications. The bands at 965 and 530 cm-1 present only in the spectra of leukaemic lymphocytes, assume particular significance. The C-H stretching region furnishes useful indications about the different ratios of the methyl groups compared with the methylene ones in the two cases. The infrared bands characteristic of the leukaemic lymphocytes seem to be due to chemical modifications not involving the DNA chain.

Necrosis of the bone marrow is rarely observed during life. Less than 50 cases have been reported, for the most part in patients with leukemia. The finding of bone marrow necrosis in children is even more rare. Of the seven cases reported, six patients had acute lymphoid leukemia and one patient had lymphocytic lymphoma. The occurrence of marrow necrosis diagnosed by aspirate and by biopsy in a child 18 months of age is presented. The necrosis was present several months before the appearance of acute lymphoid leukemia. The reasons for the presumed rarity of this pathological finding, its relationship with bone or joint pain and fever, hypotheses concerning pathogenesis, and its prognostic value are discussed.

15 cases of acute leukemia (AL) displaying a TdT+, HLA-DR+ phenotype were studied; surface immunoglobulins, T cell markers and the common acute lymphoblastic leukaemia (c-ALL) antigen were negative, as were peroxidase and non-specific esterase cytochemical reactions. All cases were extensively investigated by conventional immunofluorescence (IF) and immunoperoxidase (IP), with a panel of monoclonal antibodies (MoAb), using both light and electron microscopy, and for ultrastructural myeloperoxidase (MPO). 8 cases, which were OKB2+, BA1+, B4+, J5- and BA2- by IF, expressed the J5 antigen in IP. These cases were therefore re-classified as ALL with a weak expression of the C-ALL antigen. The other 7 cases showed an OKB2-, BA1-, B4+, BA2+ phenotype at IF and were also positive for 1 or more anti-myeloid MoAb. These features were confirmed by IP study. 4 patients also presented ultrastructural positivity to MPO. These cases were considered as proliferations of early precursor cells capable of expressing both myeloid and lymphoid features. This study, while demonstrating the heterogeneity of TdT+, HLA-DR+ AL, suggests that the cell origin of many cases may be defined by extensive immunotyping at both IF and IP level. The prognostic and therapeutic implications of these findings are discussed, also in view of the poor prognosis often observed in the more undifferentiated cases of AL.

The biological properties of normal peripheral lymphoid precursors were studied using separate colony assays for T- and B-cell colony-forming cells (T-CFC and B-CFC, respectively). Cell fractions, selected by complement-mediated cytotoxicity with monoclonal antibodies, were cultured in methylcellulose using different sources of growth factors containing (PHA-LCM2 and PHA-LCM7) or not (PHA-TCM) Interleukin-2 (IL-2). Well-differentiated T-cell colonies were only observed with IL-2-containing conditioned media (CM). Normal T-CFC displayed either an immature (E-T11-OKT3-Ia-) or mature (E+) phenotype, were quiescent cells presenting different radiosensitivity (D0 = 80 and 155 rads, respectively). B-CFC displayed the E-T11-OKT3-B1-Ia+ surface phenotype, were in DNA synthesis and were more radioresistant (D0 = 300 rads) than T-CFC. B-cell colonies could be obtained in the presence of allogeneic irradiated T cells and PHA-TCM, but not with IL-2-containing CM. When E-T11-OKT3- cells were seeded with PHA-TCM supplemented with increasing amounts of semipurified IL-2 in the presence of a fixed number of irradiated T cells, the B-cell colony growth (as assessed by the frequency of sIg+ colony cells) progressively decreased whereas that of T-cell colonies increased. IL-2-free CM (PHA-TCM) was able to induce T-cell colony growth from E-T11-OKT3- cells but addition of allogeneic irradiated T cells induced B-cell colony formation in a dose-dependent manner. Conversely, T cells enhanced T-cell colony growth in the presence of IL-2-containing CM. Furthermore, adherent cell depletion of E-T11-OKT3- cells inhibited T- but not B-cell colony growth. These results taken together suggest that T- and B-cell colonies derive from different progenitor cells which have different growth factor(s) and accessory cell requirements and indicate that T-cell colony growth is associated with inhibition of B-cell colony formation.