PubMed Health⌕ Search

Biomedical subjects

G Tosato

Publications and source records attributed to G Tosato.

121 records · Page 7Linked to original sources
PubMed1980

B cell differentiation and immunoregulatory T cell function in human cord blood lymphocytes.

The functional maturity of T and B lymphocyte populations from human newborns was evaluated using a reverse hemolytic plaque assay to detect immunoglobulin-secreting cells generated in in vitro cultures stimulated with pokeweed mitogen (PWM), a T cell-dependent polyclonal activator, and the Epstein-Barr virus (EBV), a T cell-independent B cell activator. Cord blood lymphocytes failed to produce immunoglobulin in response to PWM, but did respond with immunoglobulin synthesis to stimulation with EBV. Co-culture experiments demonstrated that cord blood T cells would inhibit immunoglobulin production by adult cells stimulated with PWM, but not with EBV. Cord blood T cells did suppress immunoglobulin production by cord blood B cells when stimulated with a mixture of EBV and PWM, indicating that cord blood, in contrast to adult blood, contains a population of suppressor T cell precursors that are easily activated by PWM. Irradiation of the cord blood T cells with 2,000 rad eliminated the suppressor activity and revealed normal helper function for immunoglobulin (Ig) G, A, and M when these T cells were co-cultured with adult B cells. Cord blood B cells co-cultured with adult T cells or irradiated cord blood T cells did produce immunoglobulin in response to PWM, but the response was significantly lower than that of adult B cells, and only IgM was produced in these cultures. These studies demonstrate that both the T and B cells of the human newborn have significant functional differences compared with the functions of T and B lymphocyte populations in adults.

Antibody Formation↗
PubMed1979

Activation of suppressor T cells during Epstein-Barr-virus-induced infectious mononucleosis.

Infectious mononucleosis is caused by the Epstein-Barr virus (EBV), an unusual human pathogen because it preferentially infects B lymphocytes and consequently activates them to produce immunoglobulins. When cultures of lymphocytes from patients with infectious mononucleosis were stimulated with polyclonal activators, unseparated cells failed to produce immunoglobulins, whereas purified B cells responded normally. Cocultures demonstrated profound suppressor T-cell activity in blood from patients with infectious mononucleosis. Early in this disease, circulating immunoglobulin-secreting cells were elevated, but during the second week their number was strikingly depressed. These data indicate that during infectious mononucleosis, EBV causes polyclonal activation of B cells, reflected by hypergammaglobulinemia and increased circulating immunoglobulin-secreting cells. Next, suppressor T cells become activated and inhibit further B-cell activation. Thus, activation of suppressor T cells in infectious mononucleosis provides a unique additional mechanism of host defense because these T cells inhibit the activation and proliferation of an important target of the causative virus.

Adolescent↗
PubMed1978

Acute lymphoblastic leukemia followed by chronic myelocytic leukemia.

Second hematologic malignancies occur rarely in patients previously treated for leukemia. This report describes a patient with acute lymphoblastic leukemia who remained in complete remission for 5 yr and then developed chronic myelocytic leukemia (CML). The original lymphoblasts were associated with a partial deletion of chromosome 21, while CML was associated with a classic Philadelphia marker, indicating the independent origin of the two leukemias.

Acute Disease↗
PubMed1975

Antibodies to Epstein-Barr virus-associated nuclear antigen and to other viral and non-viral antigens in Hodgkin's disease.

Antibody reactivity to Epstein-Barr virus (EBV)-associated nuclear antigen (EBNA) was investigated by means of the anticomplement immunofluorescence technique on sera from patients with Hodgkin's disease (HD) and from appropriate controls. Antibody levels to other EBV-determined antigens, i.e. viral capsid (VCA) and early antigens (EA), and to measles and rubella viruses, to cytomegalovirus (CMV), and to toxoplasma gondii were also measured. The results of anti-EBV antibody titrations demonstrated that anti-VCA, anti-EA and anti-EBNA reactivity was significantly higher in HD patients than in healthy subjects. There was no significant difference between the distribution of high rubella and measles antibody titers in HD and control sera. The GMT and the incidence of high titer anti-CMV and toxoplasma antibodies were greater in HD patients than in controls. The analysis of the data, according to histological subtypes, showed that the condition of lymphocyte depletion was associated in HD patients with the highest anti-EBNA antibody levels and the lymphocyte predominance with the lowest. This pattern seemed to be peculiar for anti-EBV reactivity, since anti-CMV and anti-toxoplasma antibody levels in the lymphocyte-depleted group of patients did not significantly differ from those of controls. No correlation was found between anti-VCA and anti-EBNA in individual sera of HD patients. This observation suggests that different mechanisms are probably responsible in HD for the release of EBV-related antigen from infected cells.

Adolescent↗
PubMed1975

Epidemiological study of an "hand-foot-and-mouth disease" outbreak observed in Rome in the fall of 1973.

An outbreak of "hand-foot-and-mouth disease" (HFMD) occurred in Nov. 1973 in a nursery school. Sixty-seven children were studied, 15 of whom presented clinical signs of the disease. Sixty-two percent of the HFMD cases and 18% of asymptomatics were proved to be infected with Coxsackie virus A 16. The ratio of clinical to asymptomatic infection of nursery-school children with confirmed Coxsackie A 16 infection was 58%. The accidental diffusion of the infection led to the occurrence of secondary cases. This allowed to establish the incubation period of the illness at 8 to 12 days, for 3 individual cases where a single infecting contact in a very definite time could be documented. Fecal excretion of virus was demonstrable in 2 cases up to 10-20 days, while the duration of oral excretion appeared to be somewhat shorter. Evidence was also obtained showing that infectious virus could be spread by patients during the incubation period. Virus isolations were more easily obtained in suckling mice than in cell culture.

Adult↗
PubMedDate not supplied

Use of in vitro assays in selection of compatible platelet donors.

Although HLA-matched platelet transfusions are of value in the support of some alloimmunized thrombocytopenic patients, poor posttransfusion increments can be observed following HLA-matched platelet transfusions and conversely good posttransfusion increments may result after HLA-mismatched platelet transfusions. We have explored the possibility that in vitro assays in addition to HLA typing might better select compatible donors for refractory recipients. Our studies suggested that a platelet migration inhibition assay is predictive of platelet transfusion responses in HLA-compatible and incompatible donor-recipient pairs, while lymphocytotoxicity is predictive of posttransfusion increments only in HLA-incompatible donor-recipient pairs. Granulocytotoxicity, microleukoagglutination, and capillary leukoagglutination showed no value in predicting platelet transfusion increments, either in HLA-compatible or incompatible donor-recipient pairs.

Anemia, Aplastic↗
PubMedDate not supplied

Bone marrow amyloid in patients with M-component.

Amyloid substance was looked for in bone marrow aspirates of 28 patients presenting an M-component, in association with different illnesses (plasmocytoma, chronic lymphatic leukemia, lymphocytic lymphoma, "benign monoclonal gammapathy" and liver cirrhosis). Amyloid was detected in 12 out of 20 patients with plasmocytoma (60%) and in 3 out of 8 patients with other illnesses (37.5%); it was found in 9 out of 13 cases (69.2%) presenting exclusive light chain production and in 6 out of 15 cases (40%) with a monoclonal complete Ig. Lambda type light chain, either free or Ig-bound, was slightly more often (6 cases out of 10, 60%) associated with amyloidosis than was K (9 cases out of 17, 52.9%). Bone marrow appeared to be more frequently involved than other sites considered elective such as rectal mucosa. Amyloid appeared as an intensively fluorescent substance present intercellularly in areas of variable number and size.

Aged↗
PubMedDate not supplied

IgM plasmacytoma. Report of a case and review of the literature.

IgM paraproteinaemia is described in a patient with diffuse plasmacytoma involving the pleura, lymph nodes, and kidneys. Sixteen cases of pure plasmacellular tumor (diffuse or solitary plasmacytoma and plasmacellular leukaemia) associated with IgM paraproteinaemia have only been reported. These cases and experimental data indicate that neoplastic plasma cells can synthetize IgM as well as other immunoglobulins and that this particular M component is not associated solely with Waldenström's macroglobulinaemia.

Chromatography, Gel↗