PubMed Health⌕ Search

Biomedical subjects

C Vincenzi

Publications and source records attributed to C Vincenzi.

At least 19 recordsLinked to original sources
PubMed1992

Highly concentrated urine-purified Tac peptide fails to inhibit IL-2-dependent cell proliferation in vitro.

Tac peptide, i.e., the p55 chain of the human interleukin-2 receptor (IL-2R) complex, is detectable as a soluble from (sIL-2R) in normal sera and, at increased levels, in patients with different diseases. Since several immunological abnormalities are observed in most conditions associated with an increase in sIL-2R levels, a down-regulatory effect on IL-2-dependent functions has been postulated as a consequence of binding and functional block of IL-2 by the excess of sIL-2R. To test this hypothesis, we purified sIL-2R from the urine of a patient with hairy cell leukemia and investigated the possible inhibitory effect of this peptide on the in vitro IL-2-induced cell proliferation. The urine-purified molecule was detectable by the specific immunoassay utilized to measure the serum Tac peptide and was constructed by a single polypeptide of about 50 kDa which was able to bind IL-2. Experiments performed with the IL-2-dependent murine CTLL-2 cell line and with PHA-stimulated human peripheral blood mononuclear cells showed that the purified sIL-2R at concentrations up to about 300 nM was unable to block IL-2-dependent cell proliferation. According to these data, which can be explained by the low affinity for IL-2 of the p55 IL-2R chain, it seems unlikely that in vivo the soluble Tac peptide can exert a down regulatory effect on IL-2-induced phenomena through a functional block of IL-2.

Animals↗
PubMed1992

The CD4 molecule belongs to the phenotypic repertoire of most cases of acute myeloid leukemia.

In the present study fresh leukemic cells obtained from 23 patients with acute myeloid leukemia (AML; FAB subtypes: three M1, five M2, two M3, five M4, eight M5) were investigated for the membrane expression of the CD4 molecule by cytofluorimetric analysis with an anti-CD4 monoclonal antibody (mAb). In 15 cases the presence of the CD4 mRNA was also investigated using Northern blot analysis. Membrane expression of the CD4 molecule was demonstrated in 19 out of 23 cases, and it was found to be weaker than in CD4+ lymphocytes and monocytes obtained from normal controls. Full-length CD4 mRNA was detected in 12 out of 15 (80%) cases, and AML cells positive for CD4 mRNA expression also expressed the CD4 antigen. Since the CD4 molecule expressed by T cells is associated with p56lck, a member of the src family of intracellular tyrosine kinases, we investigated whether the CD4 molecule expressed by myeloid blasts is also associated with a tyrosine kinase activity. In vitro kinase assays performed on anti-CD4 immunoprecipitates from lysates of myeloid leukemia cells from four CD4+ cases were negative for the presence of a tyrosine kinase activity. This finding was not due to the lack of expression of members of the src family since we were able to detect at least p60src and p59fyn in myeloid leukemia cells. According to our results, the CD4 molecule seems to belong to the phenotypic repertoire of most AML, irrespective of their FAB subtypes. However, in myeloid blasts this molecule is not associated with a tyrosine kinase activity as it occurs in T lymphocytes.

Blotting, Northern↗
PubMed1989

Serum levels of soluble CD8 are increased in patients with B chronic lymphocytic leukemia.

Serum levels of the soluble form of the CD8 (s-CD8) antigen were evaluated in the peripheral blood of 44 patients with B-CLL, using an enzyme-linked immunosorbent assay, and were correlated with clinical features and relevant hematological and immunological data. Increased values were observed with respect to normal age-matched controls (mean +/- S.E.M. 603 U/ml +/- 81 vs. 315 U/ml +/- 31, respectively; P less than 0.0001). This increase was observed in all stages of the disease, excluding stage 0 (mean 277 U/ml +/- 45). A general trend pointing to lower values overall in patients with less invasive disease was observed. In fact, the rank correlation test showed that the serum levels of s-CD8 correlate significantly with the WBC counts, the CD4/CD8 ratio, and also with the levels of serum immunoglobulins. On the contrary, no correlation was observed between s-CD8 levels and the absolute number of circulating CD8+ cells in individual cases. Therefore, the increase of s-CD8 is unlikely to be a mere expression of the increase of the CD8 cell number, but seems related to an increase of the activation phenomena involving the CD8+ T cell subset.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1989

Serum levels of soluble interleukin-2 receptor in hairy cell leukaemia: a reliable marker of neoplastic bulk.

In hairy cell leukaemia (HCL), the strong membrane expression of the Tac antigen, corresponding to the p55 chain of the interleukin-2 receptor (IL-2R), is associated with the presence in the serum of high levels of a soluble form of the same molecule (sIL-2R). Previous observations that therapy-induced clinical and haematologic improvement in HCL is accompanied by a progressive decrease of sIL-2R suggest a possible correlation between sIL-2R levels and tumour burden. To verify this hypothesis, we monitored the variation of sIL-2R values in 13 non-splenectomized HCL patients admitted for treatment with recombinant interferon alpha-2. The data were correlated with the estimated weight of bone marrow (BM) and spleen infiltration, which in these patients almost entirely account for the tumour mass. The regression analysis test showed a direct correlation between sIL-2R values and both BM neoplastic involvement (r = 0.63) and spleen tumour mass (r = 0.76). In addition, the correlation was further improved (r = 0.86) when sIL-2R values were correlated with the total neoplastic mass, as calculated by the sum of spleen and BM neoplastic tissue weight. These data indicate that the detection of sIL-2R in HCL is a reliable non-invasive marker of tumour burden, which can be regarded as an additional useful tool for monitoring treatment response.

Adult↗