Simultaneous flow cytometric analysis of cell surface markers and telomere length: analysis of human tonsilar B cells

Telomere Flow FISH is a recently developed method which allows the measurement of telomere length in purified subsets of cells using flow cytometry. However, the harsh conditions required for flow FISH have precluded its use with conventional cell surface staining, thus limiting its utility for large scale clinical studies. We have now developed a method which permits simultaneous analysis of cell surface markers along with telomere length estimation by flow cytometry. This new assay employs the covalent crosslinking of monoclonal antibodies conjugated with a heat stable fluorochrome to the cell surface prior to flow FISH. Using this technique we have confirmed that human germinal center B cells (IgD(-)/CD38(+)) have dramatically longer telomeres than pre-germinal center founder B cells (IgD(+)/CD38(+)). This approach simplifies the analysis of complex cell populations and will facilitate widespread investigation of telomere length in health and disease states.

Antiproliferative activity of conditioned medium from lymphocytes of neuroblastoma (NB) patient and inhibition with NB serum

Neuroblastoma (NB) is a pediatric malignancy and results in high mortality rate. Cellular immunity has been shown to play an important role in killing tumors 'in vitro'. Human lymphocytes were activated in vitro with phytohaemagglutinin (PHA) and the effect of supernatants collected at 24, 48, 72 and 96 h were tested on proliferation of human NB cell line-SK-N-MC and glioma cell line U87-MG. The SK-N-MC cells were observed to be more susceptible to the supernatants compared to U87-MG with higher inhibition of proliferation as evaluated by [3H]thymidine incorporation (P < 0.05 for 24 and 72 h and P < 0.0005 for 48 and 96 h). Conditioned medium from lymphocytes of NB patient collected at 48 and 96 h after activation inhibited proliferation (P < 0.005) of SK-N-MC cells. The presence of serum from NB patient decreased the antiproliferative activity of supernatants from normal lymphocytes and NB patient's autologous lymphocytes (P < 0.01). This preliminary data demonstrates the capability of the activation of lymphocytes from NB patient undergoing aggressive multiagent chemotherapy and controlling proliferation of tumor cells on one hand and the role of serum from NB patient in abrogating to a certain extent the effect of activated immune cells thereby protecting tumor cells, on the other hand. Both these aspects need to considered with equal importance to study mechanisms in designing strategies for immune therapies.

Ig V gene mutation status and CD38 expression as novel prognostic indicators in chronic lymphocytic leukemia

Cellular immunophenotypic studies were performed on a cohort of randomly selected IgM(+) B-chronic lymphocytic leukemia (B-CLL) cases for which Ig V(H) and V(L) gene sequences were available. The cases were categorized based on V gene mutation status and CD38 expression and analyzed for treatment history and survival. The B-CLL cases could be divided into 2 groups. Those patients with unmutated V genes displayed higher percentages of CD38(+) B-CLL cells (>/=30%) than those with mutated V genes that had lower percentages of CD38(+) cells (<30%). Patients in both the unmutated and the >/=30% CD38(+) groups responded poorly to continuous multiregimen chemotherapy (including fludarabine) and had shorter survival. In contrast, the mutated and the <30% CD38(+) groups required minimal or no chemotherapy and had prolonged survival. These observations were true also for those patients who stratified to the Rai intermediate risk category. In the mutated and the <30% CD38(+) groups, males and females were virtually equally distributed, whereas in the unmutated and the >/=30% CD38(+) groups, a marked male predominance was found. Thus, Ig V gene mutation status and the percentages of CD38(+) B-CLL cells appear to be accurate predictors of clinical outcome in B-CLL patients. These parameters, especially CD38 expression that can be analyzed conveniently in most clinical laboratories, should be valuable adjuncts to the present staging systems for predicting the clinical course in individual B-CLL cases. Future evaluations of new therapeutic strategies and drugs should take into account the different natural histories of patients categorized in these manners.

T cell responses in Hodgkin's disease: frequency distribution of IL-2 producing cells and quantitation of IL-2 produced per cell

T cell dysfunction in Hodgkin's disease (HD) is well documented. Since interleukin-2 (IL-2) plays a pivotal role in T cell proliferation, we have investigated frequency distribution of IL-2 producing phytohaemagglutinin (PHA)-stimulated lymphocytes from HD patients compared to that of healthy donors using two limiting dilution (LD) culture systems in which autologous peripheral blood lymphocytes (PBL) and Epstein Barr Virus transformed allogeneic B lymphoblastoid cell lines (EBV-LCL) have been used as feeders. The latter provided better conditions for IL-2 production by single cells, as evident from the enhanced frequencies obtained (For healthy donors: 1/67 +/- 1545.5 using EBV-LCL and 1/1123 +/- 1.7438 using autologous PBL as feeders). The data showed significantly reduced frequency of IL-2 producing cells as well as reduced quantity of IL-2 produced per cell in HD even after using/EBV-LCL as feeders, the amount of IL-2 produced per activated responder cell in HD patients being 0.825-1.3 pg/well (p < 0.001) as compared to 1.48-2.43 pg/well in healthy donors. Thus, the EBV-LCL feeders did provide better culture conditions for estimating frequencies of functional T cells. However these cell lines were unable to restore in vitro the abnormalities in functional properties of T cells in HD.

Impairment in cellular protein phosphorylation by mitogen activated lymphocytes from patients with Hodgkin's disease

T cell activation process in patients of Hodgkin's disease was studied in terms of cellular protein phosphorylation following interaction of T lymphocytes with mitogen PHA. Peripheral blood lymphocytes from Hodgkin's disease patients and healthy donors, labelled with [32P] were activated with PHA. The cell lysates were subjected to SDS-PAGE, 2-dimensional gel analysis and were autoradiographed. It was observed that lymphocytes from both Hodgkin's disease patients and healthy donors followed similar time kinetics of phosphorylation. Nine of the eleven major protein bands, resolved on SDS-PAGE in the molecular weight range of 15.7-98 kD showed reduced phosphorylation (ratios of densitometric readings taken after and before stimulation) compared to that of healthy donors. Isoelectric focusing of these major protein bands in 2-dimensional gels further resolved them into about 27 proteins. Most of these showed increased phosphorylation in lysates of activated lymphocytes from healthy donors compared to that of Hodgkin's disease patients. The results showed a defect even at an early stage in terms of inadequate cellular protein phosphorylation.

Analysis of regulation of T-cell responses by soluble inhibitory factors from the sera of patients with Hodgkin's disease

Soluble inhibitory factors (SIF) have been demonstrated in the sera of cancer patients, which interfere with the T-cell activation process. We have shown that the major contributory factor to the inhibitory effect of sera from patients with Hodgkin's disease (HD) could be the soluble form of Interleukin-2 receptors (sIL-2R). The parameters studied to show the presence of SIF include (i) inhibiton of mitogen-induced proliferation; (ii) status of high- and low-affinity IL-2R; and (iii) internalization of IL-2-IL-2R complex, by lymphocytes from healthy donors activated with mitogen in presence of HD sera. Parameters studied to show the inhibitory role of sIL2R include (i) quantitation of sIL-2R in HD sera; (ii) effect of high-sIL-2R-containing sera on mitogen-induced proliferation and detection of IL-2 in activated lymphocyte culture supernatants; (iii) effect of exogenous IL-2 supplementation; and (iv) abrogation of inhibitory activity of sIL-2R-containing sera after passing them through IL-2 affinity columns. Our results show that 6/23 HD sera tested had high inhibitory activity (greater than 50% inhibition of mitogen-induced proliferation). The SIF did not affect expression of high- and low-affinity IL-2 receptors, or internalization of the complex by activated lymphocytes. Ten of the 15 sera tested showed significantly high levels of sIL-2R. Pooled sera with high sIL-2R content inhibited mitogen-induced proliferation of normal lymphocytes with a concomitant reduction in IL-2 activity in the lymphocyte culture supernatants. When supplemented with exogenous IL-2, there was a partial recovery of the inhibitory effect. When sIL-2R containing serum pool was passed on IL-2 affinity columns, the inhibitory effect was reduced. The eluted "sIL-2R" adsorbed on the IL-2 column showed anti-proliferative effect.

Impairment in proliferation, lymphokine production and frequency distribution of mitogen-responsive and interleukin-2-producing cells in Hodgkin's disease

In this paper, we have correlated the ability of peripheral blood lymphocytes (PBL) from Hodgkin's Disease patients to proliferate in response to a mitogen, phytohaemagglutinin (PHA), with production of lymphokines interleukin-2 (IL-2) and interferon gamma (IFN gamma), accumulating in the activated lymphocyte culture supernatants. We have also studied the frequency distribution of PHA-responsive and IL-2-producing T cells from PBL using limiting-dilution analysis. We observed that the levels of IL-2 and IFN gamma in the supernatants of activated lymphocytes from patients with Hodgkin's disease were significantly reduced compared to those of healthy donors. Substage-B patients showed marked reduction in the ability to produce IFN gamma. Levels of IL-2 and IFN gamma in the culture supernatants of PBL from Hodgkin's disease patients correlated positively with proliferative responses, when analysed by linear regression (r = 0.79 and r = 0.60 respectively). However, production of the two lymphokines by activated lymphocytes from the same patients did not correlate (r = +0.04). Further, the frequencies of PHA-responsive cells and IL-2-producing cells in the PBL of patients with Hodgkin's disease (ranges 1/111-1/554 and 1/3009-1/6709 respectively) were also less than those of the healthy donors (ranges 1/80-1/181 and 1/761-1/1828 respectively). Proliferation, IL-2 production in bulk cultures and frequencies of PHA-responsive and IL-2-producing cells correlated well in individual healthy donors. Whereas, one patient (BC 11,214) with a frequency of PHA-responsive cells within normal limits had a very low frequency of IL-2-producing cells. Taken together, the results indicate abnormalities in cytokine production and frequency distribution of cells required for amplification of immune response in patients with Hodgkin's disease.

Establishment and characterization of four new squamous cell carcinoma cell lines derived from oral tumors

Four cell lines were established from squamous cell carcinomas (SCC) of the oral cavity. Cell lines AW 13516 and AW 8507 were derived from poorly differentiated SCC and epidermoid carcinoma of the tongue respectively. Cell line AW 10498 was derived from moderately differentiated SCC of the lower alveolus, and AW 9803 grew from a well-differentiated SCC of a retromolar trigone. The cultures showed typical epithelial cell morphology, numerous mitotic figures, occasional multinucleated giant cells, individual cell diskeratosis and nuclear and nucleolar abnormalities. The cell lines AW 13516 and AW 8507 were fast growers with a doubling time of 35.5 h and 31.9 h, respectively, which was independent of the initial seeding density. Cell lines AW 10498 (doubling time 52.2 h) and AW 9803 (doubling time 66 h) showed slower growth and had shorter doubling times at higher seeding densities. The presence of cytokeratins was detected in all the four cell lines by using polyclonal antikeratin antisera in indirect immunofluorescence and in Western blotting. None of the cell lines expressed major histocompatibility complex (MHC) class II antigens. MHC class I antigens were expressed by three cell lines but not by AW 9803. Flow cytometric analysis of DNA content and chromosomal studies suggested the presence of polyploidy and aneuploidy in all the four cell lines. Ultrastructural studies revealed typical epithelial cell features, such as the presence of desmosomes, tonofilaments and keratin bundles.