Neuroleukin: a lymphokine product of lectin-stimulated T cells

Neuroleukin is a lymphokine product of lectin-stimulated T cells that induces immunoglobulin secretion by cultured human peripheral blood mononuclear cells. Neuroleukin acts early in the in vitro response that leads to formation of antibody-secreting cells, but continued production of immunoglobulin by differentiated antibody-secreting cells is neuroleukin-independent. Although the factor is not directly mitogenic, cellular proliferation is a late component of the response to neuroleukin. Neuroleukin does not have B-cell growth factor (BCGF) or B-cell differentiation factor (BCDF) activity in defined assays. Neuroleukin-evoked induction of immunoglobulin secretion is both monocyte- and T-cell-dependent.

Antibody to human lymphocyte actin regulates immunoglobulin secretion by an EBV-transformed human B-cell line

Antibody against actin isolated from a human EBV-transformed lymphoblastoid B-cell line exerted an inhibitory effect on in vitro IgM secretion by a different lymphoblastoid B-cell line, LA350. This effect was dose dependent showing from 24-40% inhibition at a dilution of 1:100 and 68-80% inhibition at a dilution of 1:50. This effect was noted in the absence of changes in either total cell count or [3H]-thymidine incorporation and was reversed by co-incubation with purified rabbit thymus actin (100 micrograms/ml) but not bovine serum albumin at the same concentration. These data demonstrate regulation of immunoglobulin synthesis by antibodies against human lymphocyte derived actin in a lymphoblastoid B-cell line.

Immunoglobulin production by coeliac biopsies in organ culture

The production of immunoglobulins by jejunal mucosa during organ culture has been studied. In 18 untreated coeliac patients the amounts of IgA, secretory IgA and IgM in the culture medium were higher than in those from 17 normal controls. The results in 15 treated coeliac patients did not differ from the control subjects. Mucosal biopsies from patients with serum IgA deficiency produced very little IgA, but large amounts of IgG and IgM. The addition of neither Frazer's gluten fraction III, nor alpha-gliadin to the culture system stimulated any additional increased secretion of immunoglobulins from the untreated coeliac patients. Production of IgA and IgM by the small bowel mucosa continues during organ culture, but that of IgG appears insignificant.

T8 cell suppression of antigen- and mitogen-induced T4 cell dependent immunoglobulin production

The suppressor effect of T8 cells on antigen-induced, as compared to pokeweed mitogen-induced, T4 cell dependent immunoglobulin (Ig) production by B cells of healthy subjects was studied. The antigens used were purified protein derivative of tuberculin (PPD) and tetanus toxoid (TT). The suppressor effect of T8 cells on IgG, IgM and IgA responses in co-cultures of T4 cells and B cells was significantly stronger in the pokeweed mitogen driven system than in PPD- and TT-driven cultures under the same experimental conditions.

Effects of a human urinary mitogen on subpopulations of peripheral blood mononuclear leukocytes

We have earlier isolated, to apparent homogeneity, a 27-28 kD human basic protein (UM) from the urine of a patient with myelomonocytic leukaemia. UM is a mitogen for resting human peripheral blood mononuclear leukocytes (PBML). We have now further defined the effect of UM on human PBML and their subpopulations in 6-day cultures. Cell proliferation was measured by 3H-thymidine uptake and Ig production by the plaque forming cell (PFC) response. Whole PBML responded to UM with proliferation and an increase in PFC. The PFC response was at best equal to and frequently synergistic with that produced by pokeweed mitogen and occurred in the three major Ig classes. To test the effect of UM on subpopulations of PBML, adherent cells (AC) were isolated by plastic adherence and T and B enriched populations by rosetting with sheep red blood cells. The proliferative response of T cells needed the presence of AC whilst the effect on Ig production by B cells required both T cell help and the presence of AC. Human thymocytes also responded to UM by proliferation. The results show that, in addition to being a T cell mitogen, UM is also a T cell dependent polyclonal B cell activator.

Impairment of T cell activation in burn patients: a possible mechanism of thermal injury-induced immunosuppression

In the burn patient, the mechanisms leading to impaired T lymphocyte activity are unclear. The capacity for T cell proliferation and the expression of Tac antigen (IL-2 receptor) was assessed during the post-burn period in patients with injuries ranging from 5-68% total body surface area. T cell-dependent (polyclonal) immunoglobulin synthesis, mixed lymphocyte reaction and Interleukin-2 production were also determined in these patients and correlated with survival. Surviving patients demonstrated a transient reduction while terminal patients exhibited a permanent reduction in the number of Tac (+) lymphocytes, unrelated to the absolute number of T cells, during the post-burn period. The reduced percentage of IL-2 receptor-expressing T cells coincided with the suppressed antibody response and reduced alloreactivity. Although the concentration of IL-2 was decreased in all patients throughout the hospitalization period, surviving patients showed a gradual increase in its production while terminal patients gradually decreased to undetectable levels. Exogenous recombinant IL-2 induced a significant enhancement of in-vitro polyclonal immunoglobulin production and blastogenesis in the mixed lymphocyte reaction in immunosuppressed patients who demonstrated up to 50% reduction in the percentage of IL-2 receptor positive cells. Thus, the reduced capacity for production of and response to IL-2 after thermal injury may lead to the immunosuppression due to a lack of T lymphocyte clonal expansion. The permanent nature of this defect in patients who died from fatal sepsis may suggest a causative relationship.

Autoreactive lymphocytes in thyroid disorders. Quantitation of anti-thyroglobulin antibody formation by a specific haemolytic plaque forming cell (PFC) assay

Blood mononuclear cells (MNC) from 21 patients with autoimmune thyroiditis were assayed for secretion of immunoglobulins in vitro by a reverse haemolytic plaque forming cell (PFC) assay. An antigen-specific assay was employed to quantify anti-thyroglobulin antibody (TgAb) secreting cells. The sensitivities of the two PFC assays were similar. The antigen specificity of the Tg-PFC assay was demonstrated by the ability of free Tg to inhibit PFC formation. The number of spontaneous TgAb-secreting cells was low (median 3 IgG-Tg-PFC/10(6), range 0-35/10(6)); TgAb activity was found in 3% (range 0-11%) of total IgG-PFC. The number of spontaneous IgG-TgAb-secreting cells correlated positively to TgAb titres in serum. MNC from most patients secreted IgG-TgAb upon polyclonal stimulation in vitro for six days with pokeweed mitogen (52 IgG-Tg-PFC/10(6), range 0-478/10(6)); TgAb activity was found among 2% (range 0-8%) of total IgG-PFC. Again, pokeweed mitogen-induced TgAb secretion correlated positively to TgAb titres in serum. Finally, MNC from most patients secreted TgAb after culture with Tg. The Tg-induced response was about 1/3 of the pokeweed mitogen-induced TgAb response. Tg did not increase the production of total IgG indicating that Tg is not a polyclonal stimulus. Few TgAb-secreting MNC were discovered in euthyroid sex and age-matched control patients.

In vitro analysis of lymphocyte functions in common variable immunodeficiency: heterogeneity in B-cell defects

Ten patients with common variable immunodeficiency were classified into three groups according to the number of circulating B-cells, i.e. B-cells being absent (three patients), very low (three patients) or within the normal range (four patients). The four patients in the last group showed significant proliferative responses to the T-independent B-cell mitogen, formalin-fixed Staphylococcus aureus, Cowan I. Further study of these patients by co-cultures with allogeneic T or B-cells in various combinations with pokeweed mitogen showed that two patients had an intrinsic B-cell defect without T-cell defect. The third patient had a T-cell dysfunction (i.e. his T-cells could only help the B-cells of some individuals) resulting in a defect in Ig production. The T-cells of the fourth patient showed poor helper function towards all controls. All six patients with absent or very low numbers of B-cells in group I and II had normal T-cell helper function. This study demonstrates that the immunological defect in common variable immunodeficiency is most often a B-cell defect at different stages of their differentiation with sometimes an additional T-cell dysfunction.

Immortalization of human lymphocytes by fusion with cytoplasts of transformed mouse L cells

Fusion of mouse L929 cytoplasts with human peripheral blood lymphocytes induced lymphocyte proliferation that gave rise to lymphoid cell lines of B and T cell origin with unlimited growth potential. The immortalized cell lines were routinely grown in standard medium supplemented with fetal calf serum. Furthermore these cell lines could be propagated in chemically defined serum-free media. Each establishment of lymphoid cell lines was preceded by a proliferation phase 2 wk after cytoplast/cell fusion, which appears to be a necessary step in the immortalization process. The immortalized cells have a nearly normal human karyotype, do not form colonies in soft agar medium, and are not tumorigenic in nude mice. Cloned B cell lines produced human immunoglobulins of heavy and light chain types. No cross-reaction with DNA of herpes simplex virus, human cytomegalovirus, human T cell leukemia/lymphoma virus I and II, or polyoma virus was detected in the genome of immortalized cell lines by Southern blot hybridization. Furthermore B and T cell lines were established that appear to be free of Epstein-Barr virus genome.

Three types of swine immunoglobulin-producing tumours: lymphoplasmacytic lymphosarcoma, immunoblastic lymphosarcoma and plasmacytoma

Three types of swine immunoglobulin-producing tumours are described. Case 1 was a lymphoplasmacytic lymphosarcoma, in which IgG was intracellularly identified in the plasmacytoid cells. Case 2 was an immunoblastic lymphosarcoma, the large cells of which possessed intracytoplasmic IgG and well developed RER. Case 3 was diagnosed as a plasmacytoma. There were two distinct immunoglobulins, IgG and IgA, in single plasmacytoid cells and the RER was highly developed. The origins of the three cases are discussed according to the theory of B-lymphocyte differentiation sequences and the origins of B-cell lymphomas. The mechanism of "double producers" is discussed with reference to DNA and RNA.

Regulation of parasite-specific antibody responses in resistant (C57BL/6) and susceptible (C3H/HE) mice infected with Trypanosoma (trypanozoon) brucei brucei

After infection with 10(3) T. brucei GUTat 3.1, C57BL/6 mice produced antibody responses and controlled the first parasitaemic wave whereas C3H/He mice did not. The inability of C3H/He mice to control parasitaemia resulted from an impaired ability of parasite-induced antibody-containing cells to secrete immunoglobulin. Antibody-containing cells in infected C3H/He mice regained the ability to secrete antibody within 24 h after trypanosome elimination by treatment with Berenil, suggesting that the block in antibody secretion was maintained by living parasites or short-lived components of degenerating parasites. Infected C3H/He mice also had an impaired ability to produce a rabbit erythrocyte-specific antibody response on challenge with rabbit erythrocytes and this response recovered when parasites were eliminated from the blood 24 h before analysis. It was not possible to inhibit secretion of antibody by rabbit erythrocyte-induced plasma cells either by incubating them with serum from infected C3H/He mice or by injecting large numbers of living trypanosomes into C3H/He mice already responding to rabbit erythrocytes. The process leading to failure of parasite and rabbit erythrocyte-induced antibody-containing cells to become high rate antibody-secreting cells was not identified but did not appear to correlate with any obvious change in the intra-cellular morphology of the antibody-containing cells.

Endothelial cell enhancement of PWM induced immunoglobulin synthesis by peripheral blood mononuclear cells

The effect of various exogenous cells on the in-vitro PWM stimulation of immunoglobulin synthesis by normal human peripheral blood mononuclear cells was investigated. The accessory cells tested were bovine and human endothelial cells, bovine and human fibroblasts, normal human monocytes, and a monocyte cell line U937. Bovine and human endothelial cells boosted PWM-induced IgG and IgM synthesis, sometimes threefold. The enhancement was maintained over the 7-11 day period of culture and probably required cell to cell contact. It was not seen with the other cell types added and was, therefore, unlikely to be a consequence of an allogeneic or a xenogeneic stimulation, or a nonspecific 'feeder cell' effect.

Amiloride inhibition of DNA synthesis and immunoglobulin production by activated human peripheral blood mononuclear cells is independent of sodium/hydrogen antiport

Activation of sodium/proton (Na+/H+) antiport activity has been shown to occur as an early event in mitogenesis. Because amiloride inhibits Na+/H+ antiport activity, it is hypothesized that mitogenesis may be inhibited by amiloride. In this work, we examined the effect of amiloride on DNA synthesis as measured by [3H]thymidine uptake and immunoglobulin (Ig) production as measured by an ELISA system in human peripheral blood mononuclear cells (PBM). Amiloride at 100 microM concentration inhibited irradiated Raji cell (*R)-activated and phytohemagglutinin-P (PHA-P)-stimulated DNA synthesis by 50 +/- 11% and 72 +/- 12%, respectively. IgG production was inhibited by 71% at 100 microM amiloride concentration in *R-activated PBM. This concentration of amiloride inhibited Na+/H+ antiport activity by 92%. Because amiloride is known to inhibit other pre-replicative cellular functions such as protein synthesis, we used an amiloride analogue, dimethylamiloride, which inhibited Na+/H+ antiport activity by 90% at a concentration of 1 microM without inhibition of PBM Ig or DNA synthesis. Furthermore, neither PHA-P nor *R-stimulated PBM demonstrated an intracellular alkalinization even after 6 hr of stimulation. Similarly, T cell-enriched or B cell-enriched populations did not show intracellular alkalinization after PHA-P or *R activation. Thus, it appears that Na+/H+ antiport activation is not an early event in PBM mitogenesis. The inhibition of mitogenesis by amiloride may be due to abrogation of premitotic events such as protein synthesis.

[Induction of the switch in the synthesis of immunoglobulin classes in the RPM 1-6410t lymphoblast cell line and its clones as affected by fetal calf serum factors]

We have found that human lymphoblastoid cell line RPMI-6410t is a biochemical mutant for gene of thymidine kinase and has chromosome markers in the karyotype. Thus, this cell line can be used as a partner in somatic hybridization, in particular for producing hybridomas, synthesizing human monoclonal antibodies. We have discovered that line RPMI-6410t carries HLA-A2, -B7 and -B12 antigens of human histocompatibility complex on the cell surface. The cell membrane of this cell line contains immunoglobulins of M and D classes. RPMI-6410t cells secrete IgM molecules. It is demonstrated that induction of the switch of immunoglobulin heavy-chain classes by the factors of foetal calf serum takes place in the cells of RPMI-6410t line. Thus, the corresponding stage of B-lymphocytes differentiation in vivo is reproduced in 6410t line in vitro.

Serial immunologic studies in recipients of hepatic allografts

Thirty recipients of hepatic allografts had serial immunologic evaluations. Prior to transplant, patients had marked depression of lymphocyte subsets and impaired in vitro immunoglobulin synthesis, while phytohemagglutinin responsiveness was similar to that of controls. Following transplantation and introduction of cyclosporine and low-dose steroid therapy, there was a significant decline in both T cell subsets, but only the T4 population remained significantly depressed throughout the entire study period. The T4:T8 ratio in 5 patients who experienced acute rejection episodes was 1.4 +/- 0.6 prior to transplant. It increased to a mean of 2.0 +/- 0.6 by the time the diagnosis of rejection was made. By contrast, 12 subjects transplanted during a similar time period who did not demonstrate rejection had a T4:T8 ratio of 4.0 +/- 3.9 prior to transplant which fell to 1.5 +/- 0.6 (P less than 0.01) by 1 week post-transplant. In all 12 of these, the T4:T8 ratio fell in the 7 days post-transplant. The results indicate that monitoring the T4:T8 ratio in hepatic allograft recipients may be a useful marker for determining patients at risk for a rejection episode.

Leukapheresis in the treatment of cutaneous T-cell lymphomas

In six patients with cutaneous T-cell lymphomas (CTCL), the effect of leukapheresis (LPH) on the disease and on various immunological and haematological parameters was investigated. Enriched mononuclear cells were removed by continuous centrifugation leukapheresis from the peripheral blood of the patients. A profound and longlasting effect was seen in one patient with the Sézary variant; a moderate response was seen in two other Sézary patients. No benefit was observed in two patients with more aggressive leukaemic disease, and one patient with plaque stage MF responded on two occasions. No limiting side effects were recognized and no consistent changes of immunological or haematological parameters were observed after LPH.

Immunoglobulin production in the autologous MLR: target of the suppressor-amplifier circuit

A suppressor-amplifier circuit controlling the generation of plaque-forming cells has been demonstrated previously by us in the autologous mixed leucocyte reaction. Thus, after Leu-3+ dependent activation in an initial culture, radio-resistant Leu-2+, DR+ suppressor-amplifier cells can potently suppress Leu-3+ dependent generation of antibody forming cells, but only in the presence of fresh Leu-2+, DR- suppressor-effector cells. The target of this suppressor-amplifier circuit has been examined in a triple culture system. Suppressor-amplifier cells were activated in an initial culture; Leu-2+ cells were separated from this initial culture and transferred to an intermediate culture. After 72 h Leu-3+ helper T cells were separated from this culture and tested for their ability to support the generation of antibody-forming cells in a third culture. Such helper T cells were unable to support antibody synthesis when cultured with fresh B cells. In contrast, B cells from the intermediate culture could be activated to produce antibodies, when cultured with a fresh source of T cell help. These findings are consistent with the helper T cells being the target of the suppressor-amplifier circuit.

Identification and isolation of OKT4+ suppressor cells with the monoclonal antibody WR16

The monoclonal antibody WR16 was secreted by a hybridoma produced by fusing splenocytes from a BALB/c mouse immunized with human T-cell chronic lymphocytic leukaemia cells and the murine myeloma cell line NS-O. WR16 reacts specifically with human lymphocytes and binds to 48% of OKT4+ T lymphocytes and the majority of B lymphocytes. Human OKT4+ tonsil lymphocytes were subfractionated into WR16-/OKT4+ and WR16+/OKT4+ subpopulations by the panning technique. The capacity of these cells to help or suppress pokeweed mitogen-induced immunoglobulin (Ig) secretion by autologous B lymphocytes was monitored after 9 days of coculture. Cells of phenotype WR16-/OKT4+ enhanced Ig secretion in excess of that found with non-fractionated OKT4+ lymphocytes, whilst WR16+/OKT4+ lymphocytes suppressed Ig secretion when added to a mixture of B lymphocytes and non-fractionated OKT4+ cells. The WR16-/OKT4+ subpopulation was further fractionated by use of the MoAb Leu 8. Forty-two percent of WR16-/OKT4+ lymphocytes bound Leu 8, and cells of the phenotype WR16-/OKT4+/Leu 8+ were found to induce B-lymphocyte Ig secretion, whilst WR16-/OKT4+/Leu 8- lymphocytes were less active in this system. These data confirm the heterogeneity of the human T helper/inducer subset and indicate the existence of a population of OKT4+ lymphocytes that can suppress Ig secretion in the absence of OKT8+ lymphocytes.

Mechanisms of B cell activation in patients with acquired immunodeficiency syndrome and related disorders. Contribution of antibody-producing B cells, of Epstein-Barr virus-infected B cells, and of immunoglobulin production induced by human T cell lymphotropic virus, type III/lymphadenopathy-associated virus

Patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC) have hyperimmunoglobulinemia and increased numbers of circulating immunoglobulin-secreting cells. In this paper, we studied the basis for this B cell hyperactivity. Limiting dilution studies of B cells from seven patients with ARC and four with AIDS revealed that some B cells spontaneously produced antibodies to human T cell lymphotropic virus, type III/lymphadenopathy-associated virus (HTLV-III/LAV) (39:10(6) and 7:10(6) B cells, respectively), suggesting that chronic antigenic stimulation by HTLV-III/LAV was one contributing factor. The patients also had an increased number of spontaneously outgrowing B cells than did normals (6:10(6) vs. less than 2:10(6) B cells), suggesting that they had an increased number of Epstein-Barr virus (EBV)-infected B cells. However, fewer B cells from patients were immortalized by exogenously added EBV than were B cells from normals. In additional studies, HTLV-III/LAV induced immunoglobulin secretion (mean 2,860 ng/ml) by peripheral blood mononuclear cells from normals; this HTLV-III/LAV-induced immunoglobulin secretion required the presence of both B and T cells. Thus, antigenic stimulation by HTLV-III/LAV, increased numbers of EBV-infected B cells, and HTLV-III/LAV-induced T cell-dependent B cell activation all contribute to the B cell hyperactivity in patients with HTLV-III/LAV disease.