The cutaneous basophil response to phytohemagglutinin in chickens.

A cellular infiltrate rich in basophils was observed in chickens in skin sites injected locally with the mitogen PHA. These infiltrating metachromatically granulated cells exhibited features common to mast cells of some species (monolobed nucleus), but also resembled basophils of other species in that they circulated in the blood, and they responded to the PHA mitogen by infiltrating skin test sites. Previous literature suggests that the chicken has a single metachromatic granulated cell and our data support this notion. PHA, a known T cell mitogen, may act by causing the stimulated T lymphocyte to produce a lymphokine that is responsible for the attraction of basophils to the test site.     

Lymphocyte reaction in schizophrenia patients to the phytomitogens, concanavalin and phytohemagglutinin]

The capability of the schizophrenic patients' lymphocytes and lymphocytes of healthy persons to respond to the stimulating action of T-mutagens -- concanavalin A and PHA -- was studied. The T-cell count was determined by the method of rosette formation; the influence of adhesive cells on the lymphocyte response to mitogens was ascertained. The response to both the mitogens in the patients' lymphocyte cultures was reduced as compared to control, and the T-cell count failed to differ from the normal. The removal of adhesive lymphocytes results in the disappearance of differences between the response of the patients' lymphocytes and normal lymphocytes to both the mitogens.     

The in vitro response of thymic lymphocytes of the pig to phytohemagglutinin

The response of thymic lymphocytes of the pig to phytohemagglutinin was studied with H³ thymidine in cultures, from 0–72 hours. At the beginning of the culture period 6–18% of lymphocytes were in DNA synthesis. during the first 24 hours a sharp decrease in the number of DNA synthesizing cells was observed in both pha and control cultures, although pha cultures consistently showed small but significantly greater numbers of DNA synthesizing cells. this was followed by a definite peak in DNA synthesis and mitotic response of a minority of the cells in pha cultures between 48–54 hours, whereas in control cultures activity ceased. in addition, a small proportion of the progeny of initially DNA synthesizing medium sized lymphocytes was apparently stimulated by pha and found in mitosis by 48 hours. It was concluded that the thymus contains a fraction of lymphocytes, not in the mitotic cycle, which are capable of being transformed by pha to mitotic activity. the data also suggests some stimulation of cells already in the mitotic cycle.     

Inhibition of lymphocyte transformation responses to phytohemagglutinin by normal human plasma.

Marked variability in lymphocyte transformation responses to a suboptimal phytohemagglutinin concentration (0.1 μg/ml) was observed when peripheral blood mononuclear cells of normal subjects were cultured in media containing 15% autologous plasma. Low responses were related to the plasma and were caused by direct inhibition rather than an inability to support the response. This inhibitory activity varied greatly among different plasma specimens and was also found in human and animal serum. It appeared to be specific for suboptimal concentrations of phytohemagglutinin and could be overcome by increasing the mitogen concentration. The inhibitory activity was heat stable, was not dialyzable, and appeared to affect a very early stage of the response since a delay in addition of the inhibitory plasma reversed its effect. Our interpretation of these results is that human plasmas vary greatly with respect to their ability to bind phytohemagglutinin so that the addition of different plasmas to lymphocyte cultures stimulated by a limiting concentration of phytohemagglutinin results in marked variability of the results obtained.     

Requirement for calcium ions in lymphocyte transformation stimulated by phytohemagglutinin

Medium calcium ions were essential to the development of the lymphocyte transformation response induced by PHA. Magnesium ions could not substitute for calcium ions. Calcium exerted its influence during the induction phase of the process before DNA synthesis began since its removal after the response had fully developed did not alter subsequent levels of nucleic acid synthesis. The early development of RNA synthesis was prevented by low calcium levels indicating that calcium either directly influenced the initiation of this process or some prior event(s).     

Involvement of proteolytic acivity in early events in lymphocyte transformation by phytohemagglutinin

The stimulation by phytohemagglutinin (PHA) of DNA synthesis in cultured blood lymphocytes of guinea pig was markedly inhibited by addition of leupeptin, a well-characterized, powerful protease inhibitor of tripeptide nature. About 30 to 40 per cent inhibition was observed at 40 μg/ml of leupeptin when leupeptin was added 30 min prior to or together with PHA. Per cent inhibition by the appropriate amount of leupeptin was proportional to the amount of PHA added in the range of 0.6 to 3.0 μg of PHA at which the per cent inhibition reached maximum. This inhibitory effect of leupeptin on PHA stimulation was abolished when the lymphocytes were preincubated with PHA for more than 10 min before addition of leupeptin or preincubated with leupeptin for more than 60 min prior to PHA addition.     

Ultrastructure of lymphocytes from patients with paracoccidioidomycosis in the lymphocyte transformation test by phytohemagglutinin

The morphology and ultrastructure of peripheral blood lymphocytes from patients with paracoccidioidomycosis (PCM) and from unaffected individuals (controls) were studied before and after Ficoll-Hypaque separation and at the end of culture, stimulated with phytohemagglutinin. Patient lymphocytes were cultured in medium with autologous plasma (from the patient himself) and with homologous plasma (from an unaffected donor), while donor lymphocytes were cultured in medium with plasma from a patient or with plasma from the donor himself. The Ficoll-Hypaque mixture caused no morphological or ultrastructural changes in the lymphocytes of patients or of unaffected donors. Patient lymphocytes cultured in medium with autologous plasma showed different degrees of cytoplasmic and nuclear alterations, such as organelle dissolution, vacuoles, amorphous masses, deformed nuclei, and absence of nucleoli. Lymphocytes from control individuals cultured in patient plasma also showed ultrastructural alterations, though they were less marked, and a reduced number of blasts. Patient lymphocytes cultured in medium with homologous plasma (from a control individual) showed a morphology similar to that of lymphocytes from control individuals cultured in medium with their own plasma, although with a lower number of blasts. On the basis of the results obtained using that methodology, we draw the following conclusions: (1) separation by Ficoll-Hypaque does not seem to alter the ultrastructure of patient or donor lymphocytes; (2) patients with diffuse PCM and more markedly impaired general condition can exhibit lymphocytes with morphological and ultrastructural alterations capable of affecting their biological systems and functionality; (3) the morphological and ultrastructural abnormalities and the reduced blastogenesis observed in patient lymphocytes cultured in autologous plasma and in control lymphocytes cultured with patient plasma appear to be due to factor(s) present in the plasma of PCM patients.