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A 46-year-old woman with repeated skin infections, sore throats, laryngitis and abscesses was investigated because of low gammaglobulin on serum electrophoresis. When tested for ability to form antibodies to several antigens the patient did not respond to primary antigenic stimuli with Salmonella H or O antigens, or with keyhole limpet haemocyanin (KLH). However, she had a good secondary response to numerous agents with which she had previous contact (tetanus, diphtheria, polio and specific blood group substances). The selective impairment of cells capable of giving a primary immune response in the presence of intact memory cells gives support to the concept of a qualitative difference between these two types of cells. [ABSTRACT FROM AUTHOR]

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.

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.

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.

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.

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.

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.

In previous studies we have isolated by density gradient separation a population of relatively dense T lymphocytes capable of inhibiting the mitogenic response to concanavalin A (ConA) and phytohaemagglutinin. In this study we compared two current methods of cell separation for their relative yield in T lymphocytes able or not to respond to Con A. The present results show that cells passed through nylon wool columns--in contrast to those obtained by removal of lymphocytes which bind erythrocyte-antibody-complement complex-partially lose their ability to respond to ConA. The response lost by passage through nylon wool columns can be restored by centrifugation of the T cell suspension on a gradient of "Ficoll-Hypaque". This suggests that methods of T cells purification using density gradient separation may remove the more dense suppressor cells.

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.

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.

Cells of the different lymphoid organs in the normal adult rabbit were investigated for their capacity to respond in vitro to a number of stimuli, such as phytohemagglutinin (PHA), anti-rabbit immunoglobulin antiserum (GARIG) and allogeneic and xenogeneic lymphoid cells, and for their capacity to adsorb radioactively-labeled anti-immunoglobulin antiserum. The bone marrow cells responded minimally to PHA, GARIG, and the allogeneic and xenogeneic stimuli. The thymus cells were unable to respond to stimulation with GARIG although they responded to the other stimuli. The cells of the other lymphoid organs tested responded to all the mitogenic agents, to varying degrees. On the basis of the results presented and the findings of other investigators, it is concluded that: 1. The response of the cells to GARIG indicates a potential capacity to mediate humoral immunity and requires the presence of immunoglobulin or immunoglobulin-like recognition sites on the cell surface. 2. The response of the cells to PHA and allogeneic and xenogeneic cells indicates a potential capacity to mediate cellular immunity and does not necessitate the presence of immunoglobulin-recognition sites on the cell surface. 3. The thymus in the normal adult rabbit consists of cells capable of mediating cellular immunity only. 4. The other lymphoid organs appear to possess cells capable of mediating humoral and cellular immunity.

There exists in the rabbit a population of lymphocytes carrying immunoglobulin-like receptors on their surface. These receptors interact with antigen and with anti-immunoglobulin antibodies and appear to mediate the recognition process leading to the humoral immune response. There exists in the rabbit a second population of lymphocytes capable of reacting with phytohemagglutinin. This population of lymphocytes is different from the one capable of reacting with soluble protein antigens or anti-immunoglobulin antiserum and is probably involved in the mediation of cellular immunity.