Effect of mevalonate on in vitro reactivity of human lymphocytes stimulated by phytohemagglutinin, concanavalin A and pokeweed mitogen

Patients with mevalonic aciduria accumulate mevalonate in their and present unexplained crises of fever, lymphadenopathy, edema and mucocutaneous manifestations. In the present study, we investigated the action of mevalonate on in vitro proliferation of human lymphocytes unstimulated and stimulated by phytohemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) in order to assess possible immunomodulatory activities which could explain these symptoms. The mitogen-induced lymphocyte response was evaluated from the extent of the incorporation of 3H-thymidine into cellular DNA in vitro. Our results show that mevalonate in doses up to 5 mM does not affect human lymphocyte transformation. Furthermore, mevalonate does not reverse the suppression of lymphocyte blastogenesis caused by cortisol (100 ng/ml). These results indicate that this compound or its metabolites do not affect directly lymphocyte responsiveness.

Immunomodulatory role of thyroid hormones: in vitro effect of tetraiodothyronine (T4) on mitogen induced blastogenic response of lymphocytes.

An attempt was made to find out the immunomodulatory role of thyroid hormone, tetraiodothyronine (T4), and its effect on in vitro mitogen induced blastogenesis. Human peripheral blood lymphocytes (PBL) were subjected to phytohaemagglutinin (PHA) concanavalin-A (Con. A) and pokeweed mitogen (PWM) in presence or absence of T4. Basal blastogenic response was significantly enhanced in dose related manner by T4. PHA and Con.A induced response was depressed significantly (r = -0.975 and r = -0.945) whereas less than 50 ng T4 in presence of PHA showed mild stimulation. On the other hand, PWM induced response in presence of T4 was enhanced significantly in dose related manner.

The influence of microtiter plates from different suppliers on lymphocyte proliferation.

Microtiter plates have been popularly used for lymphocyte culture, but the influence of culture plates from different sources has not been investigated. In this study, the degree of mitogen-induced cell proliferation was investigated using six different brands of flat-bottomed plates. Lymphocytes from twelve normal donors were cultured for 96 hours with several mitogens including PHA, Con A and PWM. Spontaneous cell proliferation was slow and it did not differ significantly among the different plates. However, mitogen-induced cell proliferation showed a wide variation among the six types of plates used. The importance of selecting certain kinds of plates for specific purposes is emphasized.

Regulation of immunoglobulin secretion by T lymphocytes in human malaria.

In vitro studies were carried out on the nature of immunoglobulin synthesis and secretion by peripheral blood mononuclear leukocytes (PBMLs) and on the function of T and B cells from malaria patients. The mean values of secreted IgG and IgM concentrations of 22 malaria patient PMBLs were significantly higher than those of 20 normal PBMLs. When the suppressor T cell activity and the function of B cells in response to suppressor T cells were assayed by the cell co-culture technique, it was found that there was a decrease in suppressor T cell activity and the B cell function in response to normal suppressor T cells in malaria patients. The defects of these T and B cell functions may play some role in the immunological abnormalities seen in some malaria patients.