Procainamide induces a transitory impairment of B cell mitogenesis in beagle dogs.

Beagle dogs (3 to 6 years old) were treated with 100-150 mg procainamide HC1/kg/day. After 2, 5, and 9 months of treatment, peripheral blood lymphocytes were isolated and stimulated with pokeweed mitogen. The data demonstrated a suppression of mitogenesis only at 2 and 5 months after procainamide treatment. The lymphocytes from dogs treated for 9 months had a normal response to pokeweed mitogen. At no time during this experiment were any significant levels of serum antinuclear antibodies detected nor was any change in the number of cycling lymphocytes apparent in the experimental versus control groups. The resting membrane potential of both control and experimental groups was similar and pokeweed mitogen depolarized the cells from both groups.

Human class I MHC-restricted cytotoxic T-lymphocytes specific for human immunodeficiency virus envelope antigens.

Vaccines incorporating HIV envelope antigens are being developed for the prevention of AIDS. To determine whether HIV envelope antigens are recognized by human cytotoxic T-lymphocytes (CTL), we assessed class I MHC-restricted, HIV envelope antigen-specific cytotoxic activity of peripheral blood mononuclear cells (PBMC) from HIV-infected individuals, following in vitro stimulation. The target cells were human skin fibroblasts of known tissue type, infected with recombinant vaccinia viruses, either containing or lacking the whole HIV envelope gene. Ten out of 17 (59%) asymptomatic HIV-seropositive individuals demonstrated HIV envelope antigen-specific cytotoxicity at levels that were above those seen in HIV-seronegative controls. MHC restriction of cytotoxicity was evident in that 13 out of 19 (68%) of the targets matched for the tissue type of the donor at one or more class I MHC loci were lysed, but only two out of 18 (11%) mismatched targets (P = 0.0004). Both partial purification of effector cells and evidence of MHC restriction indicated that T-lymphocytes were responsible for the observed cytotoxicity. HIV envelope antigen-specific CTL can be detected following in vitro stimulation of the PBMC in many asymptomatic HIV-seropositive individuals. HIV envelope antigens are recognized by human CTL and are, therefore, potentially relevant immunogens for induction of HIV-specific CTL responses.

[Action of isoprinosine on the "in vitro" activation of human lymphocytes (author's transl)]. / Effets de l'isoprinosine sur l'activation des lymphocytes humains in vitro.

The action of isoprinosine on lymphocytes stimulated by optimal or suboptimal concentrations of polyclonal mitogens (ConA and PWM) was studied in 3, 5 and 7-days cultures. In some experiments, varying concentrations of isoprinosine were added to lymphocyte cultures at variuos times. Isoprinosine exerted no effect on non stimulated cells but enhanced the proliferative response in the presence of mitogens. The optimal response was obtained with a dose of 1 000 micrograms (/10(6) cells) of isoprinosine and on the 5th day in the cultures stimulated by ConA or PWM, but an enhancing effect could still be detected on the 7th day of culture. The effect seems stronger when isoprinosine is introduced earlier in the course of the cultures. Preliminary experiments suggest that isoprinosine increase the proliferation of both T and B cells and that its activity on B cells could be due to the potentiating action of helper T cells.

A syndrome associating partial albinism and immunodeficiency.

Two unrelated patients with partial albinism, frequent pyogenic infections and acute episodes of fever, neutropenia and thrombocytopenia are described. Their pigmentary dilution was characterized by large clumps of pigments in the hair shafts and an accumulation of melanosomes in melanocytes. Melanocytes had few short dendritic expansions, and keratinocytes were hypopigmented. No or few Langerhans' cells were detected in skin by electron microscopy and ATP-ase reactions. This pigmentary dilution, different from all other human albinisms, resembles the unique defect of the mutant dilute (d-d) mouse. Despite the presence of an adequate number of T and B lymphocytes, the patients were hypogammaglobulinemic, deficient in antibody production and incapable of manifesting delayed skin hypersensitivity or of rejecting skin grafts. Their leukocytes did not stimulate normal lymphocytes and could not generate cytotoxic cells during mixed leukocyte reaction. T lymphocytes of one patient were unable to exert a helper effect on the maturation of B lymphocytes into immunoglobulin-containing cells following in vitro stimulation with pokeweed mitogen. This suggests that the humoral deficiency might be secondary to a defect of helper T lymphocytes. Granulocytes did not show any morphologic abnormality, and their bactericidal activity was only moderately reduced. An increased number of polymorphonuclear leukocytes with polar distribution of Concanavaline A (Con A) receptors (capping) was found in one patient and her parents. The family histories suggest that this syndrome is transmitted as an autosomal recessive character.

Selective defect of precursor T cells associated with apparently normal B lymphocytes in severe combined immunodeficiency disease.

Two patients, one with an autosomal and the other a sex-linked form of severe combined immunodeficiency, had more than 95% B cells in their peripheral blood. Despite an increased absolute number of B lymphocytes, the patients were unable to produce serum antibodies. In each patient, geno- or pheno-identical bone marrow transplantation was followed by the visualization of a thymus shadow and the appearance of both cellular and humoral functions. Chromosome of allotype studies showed that the T cell originated from the donor whereas serum immunoglobulins were synthesized by host B cells. In these patients the pathogenesis appears to be a selective defect of bone marrow precursor T cells without concomitant intrinsic B cell defect. The successful outcome of the graft in these two patients, who are now, respectively, 5 years and 11 months of age and free of infections, indicates that the preferred form of therapy in such patients is transplantation of bone marrow stem cells, which populate the thymus and mature slowly into T cells that cooperate fully with host B cells in synthesis of antibody.

[Functional studies of T and B lymphocytes]. / Etudes fonctionnelles des lymphocytes T et B

The means for analysing T-cell activities are very limited. Indeed, the numerical estimation of the changes which take place in human T lymphocytes had to rely solely on the observation of transformed cells (blasts). However, even if various mitogens appear selective for either T of B cells, we know that both types of lymphocytes are ultimately transformed into blasts. This is particularly true in studies conducted on mixtures of T and B cells where stimulated T cells can release substances which act on B cells. On the other hand, studies with purified populations of T or B cells do not express the cellular interactions that occur naturally between these two types of lymphocytes. For all these reasons, it seemed that the estimation of " quanta " of activity unique to T lymphocytes would contribute significantly to our knowledge of this line of cells. We describe a new method of detecting the in vitro stimulation of lymphocytes based on the appearance of cells having the property to cluster several layers of sheep red blood cells (SRBC) around themselves, forming multilayer rosettes (CFC). This formation is temperature-dependent and requires trypanblue-excluding, metabolically active blastoid cells. Non-separated cells as well as purified T cells stimulated with allogeneic leucocytes (MLR), specific antigens or polyclonal mitogens (PWM, ConA) gave rise to CFC. Such multilayer rosettes were not formed by separated B cells. In the MLR, CFC were detected 48 h after beginning of cultures and increased in number thereafter just like thymidine incorporation. The response to ConA and PWM was detected earlier and gave rise to two or three peaks, the first rise in the number of CFC coinciding with the peak of thymidine incorporation, but the maximal increase occurring two or three days later. Treatment of blastoid cells with a serum specific for T cells--but not with an anti-immunoglobulin serum--abolished their ability to form ordinary or multilayer rosettes. When separated, however, on a nylon wool column, CFC were more adherent than the bulk of T cells. It is suggested that CFC form a subpopulation of T cells with distinct characteristics, allowing a direct assessment of membrane changes which take place when T lymphocytes are activated in vitro.

E1Cold cytotoxic antibodies in kidney graft recipients. / Les lymphocytotoxines froides chez les receveurs de greffe rénale

Serial serum samples from 39 renal allograft recipients were screened for cold and warm cytotoxic antibodies before and after grafting. In the group of patients who developed antibodies only after grafting, 6 had cytotoxins reactive at 37 degree C and 5 had cytotoxins reactive at 15 degree. At one year, all the patients with cold alloantibodies has functioning grafts, but none of the patients with warm antibodies had kept their graft. In three patients with cold antibodies, the cytotoxins reacted with a subpopulation of cells enriched in B lymphocytes but not with T cells eluted from nylon wool columns. This suggests that certain kinds of antibodies which appear in the blood after grafting may have enhancing properties.

[In vitro stimulation of human T and B lymphocytes by lipopolysaccharide (LPS)]. / Stimulation in vitro des lymphocytes T et B de l'homme par le lipopolyoside (LPS)

The appearance of cells (CFC) having the property to cluster several layers of sheep red blood cells around themselves has been used in our laboratory as a marker for T cell activation. In this study, enumeration of stimulated T cells was carried out by this technique, whereas enumeration of B cells was carried out with surface Ig staining using fluorescein-labelled anti-Ig antibodies or F(ab)2 anti-Ig. Lymphocytes were stimulated in vitro for various lengths of time with the polyclonal mitogen PWM, the specific antigen Varidase and LPS added at culture initiation or 16 hours after beginning of culture. Our results confirm that human lymphocytes preincubated for 16 hours before addition of LPS give rise to higher numbers of CFC and blast cells, In all cases, less than half of these blasts reacted with the F(ab)2 anti-Ig, This suggests that under these conditions, LPS is not a mitogen specific for human B cells.

[Modulation of lymphocyte proliferation by serum factors and lipopolysaccharide]. / Modulation de la prolifération lymphocytaire par des facteurs sériques et le lipopolyoside

The in vitro proliferative response of rat lymphoctes culitivated in increasing concentrations of calf serm (LCS) was measured by the incorporation of 3H-thymidine. Results showed that in contrast to the response of PHA, the response to concanavlin A (conA) was greatly dependent on the concentration of serum in the medium. Kinetics of the response of ConA indicated that increasing concentrations of LCS unblocked the non-response to supraoptimal doses of the mitogen. The supportive effect of LCS was not due to an increase in cell viability and was abolished when serum was dialyzed. By contrast, lipopolysaccharide (LPS) exerted an adjuvant effect on the response to optimal and suboptimal concentrations of ConA without unblocking the non-response to high doses. LPS facilitated the response to ConA of a distinct subpopulation of T cell isolated by separation on nylon wool columns. This in vitro model allowed us to study some factors which may be implicated in tolerance and immunity.

Immunological activities of rat lymphocytes. I. Mitogenic responses and surface markers of lymphocytes from normal, thymectomized and B rats.

Lymphocytes from the peripheral blood, thoracic duct, spleen and lymph nodes of normal, thymectomized (TX) and thymectomized lethally irradiated marrow reconstituted (TXBM or B rats) Lewis rats were studied for their ability to proliferate in vitro in the presence of Con A or PHA. At the same time the lymphoid tissues of these animals were examined for the presence of B cells or T cells by immunofluorescence staining with antiserums to rat immunoglobulins or rat brain antigens (ARBS), respectively. The specificity of ARBS fort T cells was first established in both cytotoxicity and immunofluoresecnce studies with thymocytes as well as pruified T and B cells. In various lymphoid tissues from TX and B rats, cells carrying brain antigens were found which were unable to respond to Con A and PHA. Thymectomy has a lesser effect on the response to Con A that to PHA; this was particularly true in the thoracic duct where, following thymectomy, lymphocytes continued to respond to Con A but lost their ability to respond to PHA. This suggests that the response to PHA and Con A may belong to different cells' subsets but that the ability to respond to either one of these mitogens may be impaired in cells carrying known T cell markers.