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Biomedical subjects

L A Fernandez

Publications and source records attributed to L A Fernandez.

At least 91 records · Page 5Linked to original sources
PubMed1980

Perturbation of the human immune system by lithium.

The effect of lithium on the human immune system is unknown. We studied lymphocyte responses to mitogens and their ability to produce lymphokines in four patients before and during lithium therapy. We found that with time, lithium increased lymphocyte responses to mitogens (PHA and PWM) and lymphokine production was altered from migration stimulation factor to migration inhibition factor. Although the exact mechanism is unknown, we propose that lithium has an effect on the suppressor cell system.

Adult↗
PubMed1977

The spontaneous shedding of the lymphocyte receptor for sheep red blood cells.

Cells in vitro constantly synthesize and shed macromolecules into the surrounding culture medium. B and T lymphocytes also synthesize and shed membrane components. The human T lymphocyte is identified by its ability to attach spontaneously to sheep erythrocytes. This binding is more stable at 4 degrees C and is diminished at 37 degrees C, suggesting that the receptor for sheep erythrocyte may be spontaneously shed at 37 degrees C. Therefore supernatants were obtained from human lymphoyctes at 37 degrees C and then added to sheep erythrocytes at room temperature. After washing, these sheep erythrocytes were unable to rosette with human lymphocytes. The potency of the rosette blocking activity in the supernatant was (a) highest when lymphocytes wereincuated at 37 degrees C, less at room temperature, and least at 4 degrees C, (b) increased by increasing the numbers of lymphocytes held at 37 degrees C, (c) disappeared at dilutions of the supernatants greater than 1:8, (d) was completely adsorbed by sheep erythrocytes. This suggests that lymphocytes spontaneously shed receptors for sheep erythrocytes at 37 degrees C.

Animals↗
PubMed1977

Migration inhibition produced by sodium periodate oxidation of the macrophage membrane, and reversal by sodium borohydride.

Guinea pig peritoneal exudate cells were harvested 3 to 4 days after the intraperitoneal injection of Marcol oil. The washed cells were exposed to various concentrations of sodium periodate in phosphate-buffered saline (PBS) at pH 7.4 for 10 min at +4 degrees C. The cells were then used in the in vitro migration assay, and migration was consistently inhibited at concentrations from 10(-3) to 10(-5) M. The viability of the macrophages was not affected by this treatment. Sodium borohydride (10(-3) to 10(-5) M) in PBS for 10 min at pH 7.4 reversed the periodate effect. Experiments with purified macrophages showed that sodium periodate has a direct effect on macrophage function rather than an indirect effect via the potentiation of migration inhibition factor. In support of this, the in vitro spreading of macrophages on glass substrate for 1 h has been shown to be inhibited. This spreading inhibition can also be reversed by treatment with sodium borohydride. These results provide a new approach to understanding the biological significance and role of macrophage migration inhibition.

Animals↗
PubMed1976

Cytotoxic lymphocytes in infectious mononucleosis.

Seven patients with a clinical diagnosis of infectious mononucleosis (IM) and detectable heterophil antibodies were found to have peripheral blood lymphocytes that were cytotoxic for lymphoid cells containing Epstein-Barr virus from a patient with Burkitt's lymphoma. The cytotoxic lymphocytes persisted in the peripheral circulation for up to 45 days. Patients who had had IM 1 to 5 years previously lacked such cytotoxic lymphocytes. Patients who had signs and symptoms of IM but no detectable heterophil antibodies lacked cytotoxic lymphocytes. The lymphocytes of one patient with IM showed progressive diminution of cytotoxic ability after prednisone treatment.

Adult↗
PubMed1976

E rosette formation by human t lymphocytes: a spontaneous cell mediated cytotoxic phenomenon.

The nature and significance of spontaneous association between unsensitized human T lymphocytes and sheep erythrocytes has been studied in relation to a possible cytotoxic reaction. Human lymphocytes and 51Cr labelled sheep erythrocytes when mixed in ratios of 5 or 10:1 released 70-100% of 51Cr into the supernatants. This suggests that E rosette formation may be the first step in a spontaneous T cell mediated cytotoxic reaction to sheep erythrocytes.

Animals↗
PubMed1976

Lymphocyte responses to phytohaemagglutinin: age-related effects.

Cell-mediated immunity is depressed in elderly individuals compared to young individuals, and lymphocytes from elderly individuals have been reported to have impaired lymphocyte responsiveness to stimulation by PHA after 4 days of culture. We have confirmed this observation. However, after 8 days of culture, the lymphocyte responses were greater in elderly normal individuals than in young normal individuals. Responses of lymphocytes from young individuals decreased with time from 4 to 8 days in culture, while there were increased responses with time when lymphocytes from elderly individuals were studied. When adherent cells from lymphocytes of young individuals were removed by passage through protein-coated Degalan-bead columns, the lymphocyte responses to PHA were significantly increased at 8 days. Passage of lymphocytes from elderly individuals through coated Degalan bead columns did not alter the lymphocyte responses. Removal of macrophages from the mononuclear cells obtained from young individuals did not result in increased lymphocyte responses to PHA after 8 days in culture. Removal of adherent cells appeared to have the same effect regardless of the efficiency of removing B cells. The adherent cells removed by the protein coated columns, therefore, appear to be nonphagocytic mononuclear cells which are not B lymphocytes.

Adult↗
PubMed1975

Role of renin in the pathogenesis of renal hypertension.

To test the hypothesis that renin is circulating in pressor amounts in renal hypertension, two-kidney Goldblatt hypertension was produced in rats. After hypertension had been present for a variable period of time (4 to 21 days), the ischemic kidney was removed, and an infusion of rat renin was started immediately to replace the endogenous renin that the ischemic kidney had been releasing. Since the amount of renin released by the clipped kidney was not known, the amount infused was regulated by a feedback mechanism set to keep the mean blood pressure at the same level as before ipsilateral nephrectomy. Hypertension remission was therefore prevented by this procedure. The PRA at the end of the renin infusion was similar to that prior to the ipsilateral nephrectomy. This finding indicates that the levels of the PRA circulating in renal hypertension are within the pressor range, thus supporting the hypothesis that renin plays a role in the pathogenesis of the acute or semiacute phase of renal hypertension. However, the participation of other factors cannot be ruled out since no correlation was found between PRA and blood pressure.

Animals↗
PubMed1975

Separation of T lymphocytes from normal individuals and patients with B lymphocyte chronic lymphocytic leukaemia.

Previous studies have shown that lymphocytes from patients with chronic lymphocytic leukaemia have a diminished response to mitogens which stimulate T cells. Chronic lymphocytic leukaemia is most often a disease of accumulating B cells so that T lymphocytes are diluted by large numbers of leukaemic cells. Direct comparison with the responses of normal lymphocytes to mitogenic stimulation is therefore suspect. To circumvent this difficulty, a method of isolating T cells from normal individuals and patients with chronic lymphocytic leukaemia was developed. Lymphocytes containing an average of 16.1 per cent B cells from normal individuals were applied to IgG-anti-IgG-coated Degalan bead columns and held at 4 degrees for 2 hours. The eluted cells contained less than 2 per cent B cells. When chronic lymphocytic leukaemic lymphocytes, containing an average of 68.6 per cent B cells, were applied to IgG-anti-IgG columns, the eluted cells contained 36.4 per cent B cells. To improve the purification of T lymphocytes, columns of uncoated Degalan beads were used to remove non-specifically adherent cells. Eluted lymphocytes were then applied to IgG-anti-IgG columns. This resulted in the recovery of purified populations of T cells with less than 2 per cent contamination with B cells. Patients with chronic lymphocytic leukaemia were found to have lymphocytes with either a normal density or a low density of surface immunoglobulins. B cells were successfully removed from lymphocyte suspensions in all cases of chronic lymphocytic leukaemia with a normal density of lymphocyte surface immunoglobulins. In the three cases of chronic lymphocytic leukaemia with low density surface immunoglobulins, separation by this method was unsuccessful. However, an enriched T-cell population was obtained when leukaemic lymphocytes which had lost all detectable surface immunoglobulins were passed through a column coated with heat-aggregated IgG.

Animals↗