Polyclonal activation of bone-marrow-derived lymphocytes from human peripheral blood measured by a direct plaque-forming cell assay

Polyclonal antibody secretion in human lymphocytes induced by killed staphylococcal bacteria and by lipopolysaccharide

Preparations of Staphylococcus aureus strains Cowan 1 and Wood 46 and of lipopolysaccharide (LPS) were found to act as polyclonal B-cell-activating substances for human splenic and blood lymphocytes. All three substances induced polyclonal antibody secretion in blood and spleen cell cultures, as tested against fluorescein isothiocyanate-coupled sheep erythrocytes by a modification of the local hemolysis-in-gel assay. Antibodies were of IgM class, as shown by inhibition of plaque formation by anti-IgM but not by anti-IgG or anti-IgA antisera. All these substances also consistently induced the formation of intracellular immunoglobulin and increased DNA synthesis in stimulated spleen cells. In blood lymphocytes Staph. aureus Cowan 1 induced a consistent increase in DNA synthesis, whereas Staph, aureus Wood and LPS often gave low or no increase in DNA synthesis. Peak antibody formation was observed on day 3 in spleen cells and on day 6 in blood lymphocyte cultures. Stimulation into high-rate immunoglobulin secretion occurred with all PBAs also in B-cell-enriched cell suspensions but not in T-cell-enriched cells. Optimal responses were, however, always noted in unseparated cell suspensions. It is concluded that preparations of killed bacteria can be useful tools for the clinical evaluation of both specific and nonspecific antibody-forming ability in cells from different groups of patients.

Mitogenic activation of human lymphocytes: a protein A plaque assay evaluation of polyclonal B-cell activators

Using the protein A plaque assay, the capacity of various polyclonal B cell activators to induce differentiation in human B lymphocytes was investigated. Dextran sulphate and native dextran were both virtually devoid of mitogenic properties. Lipopolysaccharide, however, was found to be a potent mitogen in human cells that, although giving rise to low DNA synthetic response, induced high numbers of immunoglobulin-synthesizing cells. Mean plaque-forming cell (PFC) numbers in healthy blood donors assayed on the optimal day (days 5-7) were 23,493 IgM/10(6) cells, 11,288 IgG/10(6) cells, and 2643 IgA/10(6) cells. Values obtained in spleen cells, peaking at days 4-6, were slightly higher. Purified protein derivative (PPD) was equally or even more effective than lipopolysaccharide (LPS) in generating PFC of different subclasses in peripheral blood with mean of 29,241 IgM/10(6), 21,269 IgG/10(6), and 3681 IgA/10(6). PPD furthermore induced a marked DNA synthetic response in human lymphocytes. These data suggest that LPS and PPD may both be used as functional markers in human cells when analysing patients with a suspected immunodeficiency state. It is suggested that cultures should be assayed using the protein A plaque assay, thereby being able not only to investigate the individual immunoglobulin classes but also to avoid the possible hazards involved in measuring antigen-specific responses in patients whose prior immunization to the antigen tested can never be totally excluded.

Conditions for induction of specific and polyclonal antibody production by Cowan 1 bacteria and by pokeweed mitogen

Cowan 1 bacteria and pokeweed mitogen (PWM) were used to induce the formation of direct plaque-forming cells (PFC) against sheep erythrocytes (SRBC) by human peripheral blood lymphocytes in vitro. It was necessary to absorb the serum supplement with SRBC before culture to obtain anti-SRBC PFC. Alternatively, sheep serum could be added to the cultures. The PFC response was specific, and the response was equally high in cultures with a mixture of absorbed and non-absorbed serum as in cultures with absorbed serum only. Cowan 1 and PWM could also induce synthesis and secretion of both IgM and IgG polyclonal antibodies. Absorption with SRBC or addition of sheep serum had no effect on this synthesis. Thus it seems likely that the induction of anti-SRBC PFC by Cowan 1 or PWM needs the presence of SRBC antigen and is the result of a synergism between mitogen and antigen. Consequently, the anti-SRBC PFC response obtained after stimulation with Cowan 1 or PWM in SRBC-absorbed serum does not reflect a true polyclonal antibody response.

Antigen-specific plaques formation of cultured mononuclear cells in head and neck cancer

Antigen-specific antibody production in vitro from peripheral blood mononuclear cells was studied for the assessment of the immune competence of patients with head and neck cancer. Optimal culture conditions were studied using inactivated Staphylococcus aureus and a saturation with IL-1 during B cell activation and pooled human AB serum on day 2. After passage of the mononuclear cells through sephadex G-10 columns, a significant increase in the antigen-specific antibody production was observed. In healthy donors a significant reduction of the antigen-specific antibody production according to the abuse of alcohol and/or cigarette smoking was detectable. Interestingly, high alcohol consumption resulted in a more pronounced decrease of the antigen-specific antibody production in vitro than excessive cigarette smoking. Patients with squamous cell carcinoma of the head and neck who are considered to be most immunodeficient did not show any antigen-specific antibody production in vitro upon activation with sheep red blood cells in the presence of Interleukin-1 (IL-1). After filtration of mononuclear cells from peripheral bloodover sephadex G-10 beads, two thirds of the patients studied became stimulable. This increase in the antigen-specific antibody production in vitro was significant, though not as dramatic as in the age- and sex-matched control groups. Interestingly, the antigen-specific antibody production raised almost to the same level as that measured in healthy donors with high alcohol abuse and cigarette consumption.

Inhibition of immunoglobulin synthesis in vitro by intravenous lipid emulsion (Intralipid)

Intravenous lipid emulsions depress lymphocyte proliferative responses and granulocyte function at concentrations found in the blood circulation during their administration. The effects of Intralipid, a widely used intravenous lipid emulsion, were measured on immunoglobulin production in vitro by pokeweed mitogen-activated lymphocytes as a test of B-cell function. Intralipid decreased IgG, IgM, and IgA production at soybean oil triglyceride concentrations of 2.5-20 mg/ml occurring in the blood circulation during Intralipid infusion. The effects on IgM and IgA production were highest and that on IgG production lowest. Hydrocortisone-sensitive and concanavalin A-inducible suppressor cells were more sensitive to Intralipid than other cell populations. In vivo Ig production may not be equally disturbed, inasmuch as Intralipid concentrations in the lymph nodes and the spleen may be lower than in the blood circulation. However, care should be taken to prevent Intralipid concentrations from becoming high enough to depress immune responses.

Cell-mediated and humoral immune responses to total hip replacement under spinal or general anaesthesia

Regional anaesthesia has many advantages over general anaesthesia in hip surgery. When the effects of total hip replacement under spinal or general anaesthesia were compared in 22 patients, the only difference between the groups occurred in PHA-induced lymphocyte proliferative responses. In contrast, no differences between the groups were observed in leucocyte or differential counts, lymphocyte or subtype counts, most mitogen-induced lymphocyte proliferative responses, NK-cell activity, IgG, IgM or IgA production by unstimulated or PWM-stimulated lymphocytes, proliferative responses of control lymphocytes with 15% patient serum, or chemiluminescence values in phagocytosis of zymosan opsonized with patient serum. Thus, regional anaesthesia is indicated in total hip replacement for reasons other than the immune response.

Candida albicans: mannan and protein activation of cells from various human lymphoid organs

Challenging human lymphocytes with soluble cytoplasmic Candida albicans protein antigen (CP) and cell-wall-derived C. albicans mannan (CM) induced DNA synthesis and antibody secretion measured as plaque-forming cells (PFC) in an indirect haemolytic assay. Enriched T and B lymphocytes responded poorly to CP and CM. However, when adherent cells were added, T and B cells responded well to CM, but not to CP. Peripheral blood lymphocytes responded more strongly to CP than to CM, with peak stimulation on day 7. Bone marrow cells displayed similar DNA synthetic responses as blood lymphocytes, but peak stimulation occurred on days 4 and 5 for CP and CM, respectively. Cells from the various parenchymal organs, including adenoid, tonsil, and spleen, showed peak DNA synthesis ranging from days 3 to 5 with a tendency for CM to produce an earlier response than CP. In contrast to that observed in blood and bone marrow cells, CM induced a higher DNA synthesis in cells from parenchymal organs than CP, which gave low stimulations. PFC, like DNA synthesis, in blood and bone marrow cells responded best to CP, whereas spleen cells showed the highest response to CM. In blood and bone marrow cells, only IgG PFC were induced, but in spleen cells IgA and IgM PFC were also stimulated by CM. Fetal liver cells responded poorly to these two Candida preparations. CM but not CP stimulated DNA synthesis in umbilical cord blood lymphocytes and IgG, IgA, and IgM in spleen cells, suggesting that CM is a polyclonal activator and that CP acts as an antigen.

Human large granular lymphocytes induce immunoglobulin synthesis after bone marrow transplantation

Following T cell-depleted bone marrow transplantation, helper T cell numbers remain depressed for some months. Nonetheless, functional B cells can be adoptively transferred to the recipients of such grafts, where they continue to secrete antibody. We now show that immunoglobulin production by these transferred B cells is induced by activated large granular lymphocytes (LGL) which circulate in the recipients in substantial numbers during the immediate post-transplant period. The LGL are CD3 negative and therefore provide help in an antigen-unlinked manner. Helper effects for autologous (donor) B cells are augmented by the addition of anti-LFA-2 (anti-CD2) which appears to act by blocking recruitment of LGL inhibitory to developing B cells. In contrast antibody to the beta chain of LFA-1, which effectively reduces natural killer activity of LGL, does not influence their helper function. The peripheral blood LGL fraction thus contains both helper and cytotoxic activity, which can be distinguished by appropriate monoclonal antibodies.

Effect of doxycycline on immune response in mice

The effect of doxycycline on immune response has been studied in mice, cell-mediated immunity being evaluated with the split heart allograft technique. Survival duration of heart transplants in animals treated with 2.5 mg of doxycycline per kg per day from the day of transplantation until rejection was slightly but significantly longer than in untreated animals, 18.8 days (P less than 0.05) as compared with 14.5 days. In doxycycline-treated animals, both agglutinating and hemolytic antibody response to sheep erythrocytes was slightly but significantly decreased, though there was no inhibition of splenic production of antibodies to sheep erythrocytes (as measured by the number of plaques of hemolysis detected). The results show the immune response in mice to be only moderately inhibited by doxycycline. The relevance of experiments in mice is also discussed.

Rearrangements of T-cell receptor gene YT35 in human DNA from thymic leukaemia T-cell lines and functional T-cell clones

An essential property of the immune response is its ability to distinguish between self and non-self and to generate enormous diversity in antibody and T-cell immune responses. Although the genetic and molecular mechanisms responsible for antibody diversity have now largely been elucidated, the structure of the T-cell receptor and the diversification of the receptor repertoire have only recently become amenable to study. One approach has involved immunochemical studies of the protein precipitated by monoclonal antibodies which react specifically with the immunizing T-cell clones. Another approach has been to clone and sequence a human or a murine T-cell specific message that may specify part of the T-cell receptor. We present here results of Southern blot analysis of non-T, immature T, and mature T-cell genomic DNA, and provide evidence that rearrangements of the YT35 sequences do occur in the DNA of thymic leukaemia T cells. This suggests that YT35 codes for at least part of the T-cell receptor and that rearrangements occur at this early stage of thymic ontogeny. Furthermore, DNA rearrangements are present in lymphocytes with phenotypic and functional characteristics of helper, killer, or suppressor T cells. We conclude that the three subpopulations of T cells operate via receptor molecules encoded by the same gene family.

Presence of T-cell receptor mRNA in functionally distinct T cells and elevation during intrathymic differentiation

Understanding the differentiation of functionally distinct subsets of T lymphocytes is essential to unravel their crucial role in the immune response and awaits knowledge of the assembly and expression of genes encoding the T-cell receptor. Recently, we have cloned and sequenced complementary DNA that may specify part of the human T-cell receptor. The deduced protein sequence showed extensive similarity to the entire length of mammalian immunoglobulin light chains. In addition, sequences corresponding to this message undergo somatic rearrangements and are assembled from non-contiguous genomic sequences into a single mRNA molecule, a mechanism similar to those found in the generation of immunoglobulin messages. A related molecule from the mouse was also isolated independently by Hedrick et al. Here we show that the putative T-cell receptor mRNA is expressed at a relatively high level during intrathymic differentiation before decreasing about 10-20-fold in normal, mature peripheral blood T cells and that it can also be detected in T-cell clones with helper and cytotoxic functions, as well as in at least one clone with suppressor properties.

Spontaneous and pokeweed mitogen-induced in vitro IgG production specific for S. aureus cell wall determinants in man

A system has been established to produce in vitro IgG specific for cell wall determinants of S. aureus by human peripheral blood mononuclear cells (PBMC). PBMC of healthy individuals, of patients with S. aureus infections and of patients with other bacterial infections were cultured for 12 days. In the culture supernatants (SN) total IgG was determined by a competitive RIA, and IgG to purified cell walls (PCW) of S. aureus strain H by a two step ELISA. PBMC of 11 healthy persons produced anti-PCW IgG upon stimulation by pokeweed mitogen (PWM). This indicates the presence in some healthy persons of circulating B cells which can be induced in vitro to synthesize PCW specific IgG. PBMC of S. aureus infected patients, however, synthesized anti-PCW IgG in culture medium alone. This is the first description of spontaneous in vitro production of specific IgG during a bacterial infection and may be analogous to short phases of spontaneous specific IgG production described after immunizations and viral infections. Finally, compared to healthy individuals, an increased total IgG synthesis in vitro by PBMC obtained from patients with S. aureus and from patients with other severe bacterial infections was found. It is concluded that this polyclonal B cell activation has been initiated in vivo. Its biological significance is unknown.

Immune responsiveness following intratracheal inoculation with Histoplasma capsulatum yeast cells

Splenic in vitro immune responses from C57B1/6 mice have been evaluated after intratracheal (i.t.) or intravenous (i.v.) inoculation with live Histoplasma capsulatum yeast cells. Significant (P less than 0.005) numbers of cells reactive to heat killed H. capsulatum (HK-Hc) were present 1 week after i.t. inoculation with 5 X 10(5) viable yeast cells. In contrast, blastogenic responses to HK-Hc were not detected until 3 weeks after i.v. H. capsulatum inoculation. Examination of non-specific immunity, i.e. mixed lymphocyte responses to alloantigens and antibody formation to sheep erythrocytes, revealed a significant (P less than 0.005) and transient depression of these responses 1 week following i.t. H. capsulatum inoculation. The non-specific decreases associated with early (1 week) i.t. infection were not mediated by suppressor cells but were related to the number of viable yeast administered.

Human B cell growth factors overcome T cell-mediated inhibition of specific antibody production: a possible mechanism for the exacerbation of autoimmune disease

Under normal circumstances, antigen-dependent antibody production in man requires autologous T cells, B cells and macrophages. If allogeneic T cells are substituted, then antibodies are not synthesized, due to the development of inhibitory interactions. Addition of B cell growth and differentiation factors changes this pattern of response, and allows antibodies to be produced even when allogeneic T cells are the source of help. There is evidence that such B cell growth factors are released during most normal immune responses: we suggest that their ability to allow B cells to escape from inhibitory interactions and secrete antibodies, may underlie the observed exacerbation of certain autoimmune diseases by intercurrent infection.

Immunologic studies of three family members with the immunodeficiency with hyper-IgM syndrome

We report the results of immunologic studies in a family in which the father (III-5) and his two daughters (IV-7 and IV-8) had the hyper-IgM syndrome (IHIS). Repeated immunoglobulin levels done on III-5 showed a typical IHIS pattern: low IgG, traces of IgA, and high IgM. IV-7, who also had stage IIA Hodgkin's disease, had a similar pattern except after irradiation therapy to sites of disease, when IgM dropped to normal range while IgG and IgA remained low. IV-8, on the other hand, had normal IgG and IgA and moderately elevated IgM until age 18 months, when she gradually developed the IHIS pattern. All three patients had normal numbers of B cells (sIg) and of T cells, although IV-7 had increased suppression. Finally, all three patients shared the A3,B7 haplotype and none was blood type O. IHIS is not necessarily X linked, is not associated with blood type O, and appears to be heterogeneous even within the same family. Inheritance in this family is apparently autosomal dominant and the father may represent a new mutation.

In vitro analysis of lymphocytes: markers and functions

Current dermatologic literature is becoming replete with articles elucidating current concepts in the pathophysiology of lymphocytic diseases. Much of this knowledge emanates from the increasingly sophisticated and complex methods of identifying lymphocytes. No longer does it suffice to know that B lymphocytes or T lymphocytes are present, but rather the key information involves knowing what subsets of these cells are present and/or their functional status. The reader attempting to assimilate all this information is thus confronted with an overwhelming, as well as frequently changing, array of analytic methods. This paper is presented as a review of thinking, principles, and methods employed in research on lymphocytic disease.

Cytofluorographic analysis of pokeweed mitogen-stimulated human peripheral blood cells in culture: age-related characteristics

By use of monoclonal antibodies and flow cytometry techniques, peripheral blood mononuclear cells from young (20-30 years) and elderly (70+ years) subjects were analyzed before and after culture with pokeweed mitogen to gain insight into the cellular interactions responsible for the decreased B cell response observed in culture samples from the elderly. Data analysis of surface immunoglobulin-positive cells demonstrated no difference in the percentage of B cells in the elderly, while both plaque-forming cell and intracytoplasmic immunoglobulin assays showed significantly reduced B cell maturation (P = less than 0.01) compared with young controls. The B cell defect was shown to be functional and not a result of failure to proliferate and survive during incubation. Surface marker analysis of T cell subpopulations demonstrated a definite shift (P = less than 0.01) in the helper/suppressor T cell ratio in cultured samples from the elderly group (3.9) compared with young subjects (1.2). In addition to the absolute increase in the helper T cell population, forward-angle light scatter analysis demonstrated that, compared with young controls, a greater portion of the helper T cell population in the elderly subjects had characteristics of activated, blast-sized cells. The data reported in this study suggest that in the elderly group there is a functional immunoregulatory imbalance in the helper T cell subset.

Binding of sheep erythrocytes in chronic lymphocytic leukemias of B-cell origin

Two patients with B chronic lymphocytic leukemia having leukemic cells that bind sheep red blood cells by different mechanisms are described. In the first case, rosette formation was mediated by the anti-sheep erythrocyte activity of a monoclonal surface IgMk, related to Forssman antigen. In the second, E-rosette formation was found to be independent of both surface immunoglobulins and the classic E-rosette receptor since the leukemic cells were recognized neither by the OKT-11 monoclonal antibody nor by other markers specific to T-cell lineage. Evaluation of these rare cases emphasizes that detection of surface immunoglobulins and spontaneous rosetting are not sufficient for the characterization of leukemic clones and raises some doubts concerning the use of available surface markers in the characterization of lymphoproliferative disorders.

Human anti-tetanus antibody response in vitro: autologous and allogeneic T cells provide help by different routes

Human B cells will make anti-tetanus antibody in vitro in the presence of antigen and T cells. These T cells may be autologous, but allogeneic T lymphocytes function equally well provided they are first irradiated. The allogeneic cells provide help by a different route. Co-culture of allogeneic cells produces a degree of polyclonal activation of B cells and a much higher level of IgM anti-tetanus antibody than autologous cultures. Depletion of tetanus toxoid or alloantigen-reactive T cells by 3H-thymidine suicide indicates that in autologous cultures help for anti-tetanus toxoid antibody production is provided by antigen-reactive T cells while in allogeneic cultures antibody production is dependent on the presence of alloreactive T cells. The implications for assessing human T and B cell function are discussed.

In vitro generation of antigen-specific hemolytic plaque-forming cells from human peripheral blood mononuclear cells

We have described a culture and assay system for the sensitization of human peripheral blood mononuclear cells with a T cell-dependent antigen, sheep erythrocytes, in the absence of nonspecific stimulatory agents and with the subsequent generation of macroscopic hemolytic plaques. We have shown that the antibody produced by the plaque-forming cells generated in this culture system is specific for the sensitizing antigen, and that the plaques created are not false plaques because their formation is inhibited by cycloheximide. The success of this system can be attributed to several critical factors including large numbers of peripheral blood mononuclear cells (5 x 10(6) culture), a prolonged period of incubation (10-11 d), continuous rocking during the entire period of incubation, culturing in large (35-mm) flat-bottomed culture dishes in the presence of human plasma, and the appropriate antigen concentration (5 x 10(6) sheep erythrocytes/culture). Furthermore, the generation of macroscopic hemolytic plaques requires plaquing sensitized peripheral blood mononuclear cells in target cell monolayers fixed in an agarose matrix with an incubation period of 2-3 h. We have further shown that the antigen-specific response measured by this system is dependent on adherent cells and T lymphocytes. At least one population of the helper T cells is sensitive to 2,000 rad irradiation. This system is simple, sensitive, and should serve as an effective tool for the analysis of cellular interactions involved in the generation of human antigen-specific plaque-forming cells, the genetic control the human immune response, and the pathophysiology of altered immunoregulation in disease.

Polyclonal B-cell activation induced by extracts of Gram-negative bacteria isolated from periodontally diseased sites

The objective of this research was to determine whether gram-negative bacteria frequently isolated from periodontally diseased sites contained polyclonal B-cell activators. Polyclonal B-cell activation, which results in nonspecific activation of multiple B-cell clones was analyzed by a hemolysis-in-gel assay designed to detect a broad range of antibody specificities. Extracts from numerous bacterial strains, including Bacteroides gingivalis, Bacteroides melaninogenicus subsp. melaninogenicus, B. melaninogenicus subsp. intermedius, Fusobacterium nucleatum, Selenomonas sputigena, Capnocytophaga ochracea, and Actinobacillus actinomycetemcomitans, were tested. Extracts of the above organisms were found to stimulate polyclonal antibody responses in cultures of normal human peripheral blood lymphocytes, although the magnitude of stimulation varied among the extracts. Optimal antibody-forming cell responses were found at stimulator doses between 5 and 1,000 micrograms/ml. We conclude that the resident gram-negative subgingival flora associated with periodontal lesions possesses potent polyclonal B-cell activators. These activators may contribute to disease pathogenesis by inducing B lymphocytes to produce antibody, osteolytic factors, or both and possibly other mediators of inflammation.

Polyclonal activation of human B lymphocytes by Fc fragments. I. Characterization of the cellular requirements for Fc fragment-mediated polyclonal antibody secretion by human peripheral blood B lymphocytes

Fc fragments derived from human immunoglobulin were found to be capable of inducing both a proliferative and polyclonal antibody response in human peripheral blood lymphocyte cultures. The cell population proliferating in response to Fc fragments belongs to the B cell lineage. Expression of polyclonal antibody formation requires the presence of both adherent monocytes and T cells. The role of the monocyte is to enzymatically cleave the Fc fragment into 19,000 mol wt Fc subfragments that are then able to induce polyclonal antibody secretion. Stimulation of polyclonal antibody production by Fc subfragments occurs in the absence of adherent monocytes but still requires the presence of T cells.

Fractionation and characterization of the immunosuppressive substance in crude extracellular products released by Streptococcus intermedius

The noncytotoxic immunosuppressive substance detected in crude extracellular products of Streptococcus intermedius (CEP-SI) was fractionated by two steps of preparative isoelectric focusing in sucrose gradients using ampholytes of pH range from 3.5 to 6 and 4 to 5, respectively. The in vitro and in vivo suppressor effects of the most highly purified fraction of CEP-Si, designated fraction 3' (F3'EP-Si), corresponded well with those of the original CEP-Si. F3'EP-Si was sensitive to the effects of alpha, gamma, and delta chymotrypsin, trypsin, and heating. It contained approximately 1% of the total amount of protein found in the original CEP-Si, corresponding to a single band on analytical isoelectric focusing, stainable by Coomassie Blue and of isoelectric point of 4.25. The absorption spectrum of F3'EP-Si had a maximum at 260 nm but its biological activity was resistant to deoxyribonuclease and ribonuclease A and it did not contain material stainable by methylene blue. It was also resistant to neuraminidase and did not contain material stainable by periodic acid schiff. We conclude that the substance responsible for the suppressor activity of CEP-Si is a protein of molecular weight approximately 90,000, which adheres to Sephadex of cellulose acetate and forms complexes with other, nonactive constituents of CEP-Si.

Impaired B-lymphocyte reactivity in patients with Hodgkin's disease and non-Hodgkin-lymphomas

The generation of immunoglobulin-secreting cells upon stimulation with pokeweed mitogen was studied in patients with Hodgkin's Disease (HD) and non-Hodgkin lymphomas (NHL) using a reverse hemolytic plaque assay. The experiments revealed that the majority of the patients in both groups had greatly diminished responses of their peripheral B-lymphocytes. Whereas in NHL patients an intrinsic B-cell defect is the most likely explanation for the impaired B-cell reactivity, the situation in HD appears to be more complex. In some patients with an active stage of the disease, suppressor cells were found to cause the unresponsiveness: in other patients, an intrinsic B-cell defect as well as a defect of the T helper cells were responsible for the diminished responses. The results further suggest that the immune defect in patients with HD is reversible and can be corrected by therapy.

The role of mitogens and antigens in the generation of antibody-producing human B lymphocytes

Satisfactory experimental systems with which to study the antigen specific humoral immune response of human peripheral blood lymphocytes have not been available until recently. A commonly used method for the study of antibody production by human lymphocytes is that developed by Fauci and Pratt. This system is considered to be antigen nonspecific since the antigen against which the determined antibody is directed is not added to the cultures. We show here that the assumption of the Fauci-Pratt system being antigen nonspecific is not justified. An essential ingredient of this culture system is human serum that has been exhaustively absorbed with antigen (sheep red blood cells). This absorption procedure causes shedding of highly immunogenic antigenic fragments whose immunogenic activity we demonstrated using a recently developed antigen-dependent culture system. In the latter system, we have shown that the control of suppressor cells is a critical factor for the successful induction of antibody responses, particularly in view of the fact that lymphocyte mitogens must be added to cultured human lymphocytes to support their responsiveness. Appropriate timing of mitogen addition to the cultures was found to be an effective means of preferentially stimulating helper or suppressor activity. Pokeweed mitogen, a mitogen known to act on B and on T lymphocytes, Stimulates B cells responses readily but abrogates them prematurely by the simultaneous activation of suppressor cells. When pokeweed mitogen is added to an ongoing response with a delay of 48 hr, it enhances antibody responses markedly, presumably by providing additional help to B cells at a time when they have lost susceptibility to suppressor-cell effects.

Polyclonally triggered B cells in the peripheral blood and bone marrow of normal individuals and in patients with systemic lupus erythematosus and primary Sjögren's syndrome

Numbers of B cells spontaneously secreting Ig (IgG, IgA, and IgM) were determined by a plaque-forming cell (PFC) assay simultaneously in the peripheral blood and bone marrow of normal individuals, patients with systemic lupus erythematosus (SLE), and patients with primary Sjögren's syndrome. Normal individuals had 382 (+/- 89) PFC per 10(6) mononuclear cells in peripheral blood. Patients with either active or inactive Sjögren's syndrome had normal numbers of spontaneous Ig-secreting cells in peripheral blood (P greater than 0.2). Conversely, patients with inactive as well as active SLE had markedly increased spontaneous PFC (P less than 0.05 and P less than 0.001, respectively). Patients with active SLE had significantly greater PFC than patients with inactive SLE; 3,984 (+/- 960) versus 1,605 (+/- 527) PFC per 10(6) mononuclear cells (P less than 0.05). The lack of increased numbers of activated B cells in the blood of patients with Sjögren's syndrome was not explained by a preferential sequestration of activated B cells in the bone marrow. However, of particular interest was the finding that the bone marrow served not only as a major source of virgin B cells but as a lymphoid organ of either in situ activation of B cells or sequestration for activated B cells. Normal individuals had approximately a 20-fold relative increase of activated B cells per 10(6) mononuclear cells in the bone marrow compared to peripheral blood, while patients with inactive and active SLE both had a 35-fold relative increase in activated B cells in bone marrow compared to peripheral blood. The potential relevance of circulating activated B cells and their sequestration in lymphoid organs is discussed concerning the discrepancy in this regard between Sjögren's syndrome and SLE, and our understanding of the significance of polyclonal B cell activation in the pathogenesis of these diseases.

The maintenance of B-cell and T-cell function in frozen and stored human lymphocytes

The objective of this study was to identify and test a convenient means for long-term storage of lymphocytes taken from clinically characterized patients without losing B- or T-cell function. Accordingly, peripheral blood lymphocytes were frozen and stored, and portions of each sample were subsequently assayed for T-cell blastogenic response and B-cell Jerne plaquing at various time intervals after freezing. A comparison of the cell counts of fresh and frozen cultures indicated that cell were recovered after freezing. Furthermore, these cells showed no significant differences in (i) cell viability; (ii) blastogenic response to antigens of Actinomyces maeslandii, Bacteroides melaninogenicus, Fusobacterium nucleatum, and tetanus toxoid; (iii) blastogenic response to phytohemagglutinin and pokeweed mitogen; and (iv) polyclonal B-cell response to pokeweed mitogen as measured by the direct Jerne plaque assay. The retained blastogenic and plaquing responses seen in frozen cultures indicated the maintenance of both T-cell and B-cell function, respectively. This is the first reported demonstration of Jerne plaquing of normal human lymphocytes after freezing. It appears that freezing techniques provide a means for repeating and extending both T- and B-cell assays using frozen stored portions of the same cell samples.

Polyclonal activation of human peripheral blood B lymphocytes by formaldehyde-fixed Salmonella paratyphi B. I. Immunoglobulin production without DNA synthesis

A "new" polyclonal activator of human peripheral blood B cells, formaldehyde-fixed Salmonella paratyphi B, is described. This bacterium does not stimulate cell proliferation as measured by incorporation of tritiated thymidine but does stimulate a subpopulation of B cells to secrete large amounts of IgM, IgG, and IgA in 7-day cell cultures. The immunoglobulins (Ig) produced by cells responding to S. paratyphi B are not specific antibodies against the bacterial antigens. In comparison with other B cell activators (pokeweed mitogen, Staphylococcus aureus Cowan I, and lipopolysaccharide), S. paratyphi B stimulation produced greater amounts of IgM but less IgG than pokeweed mitogen (PWM) or S. aureus Cowan I; lipopolysaccharide failed to stimulate significant Ig production on day 7 in most cases. In addition, the response to S. paratyphi apparently did not require T cell collaboration. These results suggest that the B cell subpopulation(s) responding to S. paratyphi B may be more differentiated B cells than those responding to either PWM or S. aureus Cowan I. Peripheral blood mononuclear cells from five patients with common variable immunodeficiency without evidence of abnormal suppressor T cells or monocytes failed to respond to S. paratyphi B, whereas cells from two of the same patients responded well to S. aureus Cowan I and partially to PWM. Thus, S. paratyphi B appears to be superior to other B cell activators for studies of B cell function in normal and abnormal states.

PPD-induced viral antibody production in human blood lymphocytes

The ability of purified protein derivative of tuberculin (PPD) to induce polyclonal antibody production in cultures of human blood lymphocytes was studied. IgG and IgM were determined by the enzyme-linked immunosorbent assay (Elisa). PPD induced both IgM and IgG production, with a predominance of IgM. PPD usually stimulated a stronger IgM response but a weaker IgG response than did pokeweed mitogen (PWM). Supernatants of PPD- or PWM-stimulated lymphocyte cultures were tested for antibodies to morbilli, rubella and herpes simplex by Elisa. PPD as well as PWM induced viral antibody production in lymphocytes of donors who had serum antibodies to the corresponding viral antigens. Production of viral antibodies of IgG class but not of IgM class was demonstrated. The PPD-induced antibody response was T cell-dependent.

Differential effect of human interferon on normal and neoplastic T- and B-cell lymphocytes

The effect of human interferon (HIF) on the growth and function of normal and neoplastic proliferating human T and B cells was studied. Cell cycle analysis by flow-cytometry showed that up to 2000 units of HIF had little effect on the proliferating fraction (that is, the present S + G2 + M phases of the cell cycle) of normal T cells grown continuously wit growth-promoting factor from PHA-stimulated lymphocytes, while 500 units of HIF suppressed the percent S + G2 + M of the acute lymphocytic leukemia (ALL) T-cell line, MOLT, by 36%. Up to 2000 units of HIF had a moderate enhancing effect on the percent S + G2 + M of PWM-stimulated lymphocytes. In striking contrast, a single unit of HIF caused nearly 40% suppression of the percent S + G2 + M of Daudi, a Burkitt's lymphoma cell. One-thousand units of HIF did not decrease the number of antibody-forming normal cells, and up to 500 units of HIF did not inhibit the total Ig secreted by these cells. These results suggest that amounts of HIF affecting the proliferation of some neoplastic lymphoid cells has little effect on the proliferation of normal T and B cells. In addition, HIF does not appear to affect polyclonal induction of B-cell differentiation.

Effect of fusidic acid on the immune response in mice

The effect of fusidic acid on the immune response in mice was studied. At the nontoxic dose of 500 mg/kg per day, the cell-mediated immunity was strongly inhibited. A marked and significant prolonged survival of split-heart allografts in treated animals was detected. The survival time of allografts in mice receiving fusidic acid from the day of the transplantation until the grafts were rejected was 26.1 days compared with 14.5 days in untreated animals. In mice treated also before the transplantation, the mean survival of the allografts were even longer. The phytohemagglutinin response, as well as the mixed lymphocyte culture stimulation of spleen lymphocytes from mice given 500 mg of fusidic acid per kg daily for 1 week, were significantly inhibited. At the same dose there was also a significantly decreased primary antibody response to sheep erythrocytes, but it was of limited biological significance. The immunosuppressive effect in animals treated with a human therapeutic dose of fusidic acid (25 mg/kg per day) was less pronounced but significant. The relevance of these results is discussed.

Heterogeneity of b lymphocyte differentiation in severe combined immunodeficiency disease

Pokeweed mitogen-induced B lymphocyte differentiation in vitro into antibody secreting plaque-forming cells (PFC) was investigated in nine patients with severe combined immunodeficiency having variable proportions of circulating B lymphocytes. When cultured by themselves, the peripheral blood mononuclear cells did not respond to stimulation with pokeweed mitogen in any patient. In the presence of irradiated allogeneic T cells as helpers, however, PFC responses were elicited in lymphocyte cultures from peripheral blood and/or bone marrow in some patients. In one of these patients, results of allogeneic co-culture experiments were suggestive of genetically restricted suppressor cells. In a single patient with deficiency of the enzyme adenosine deaminase, PFC were generated in bone marrow lymphocyte cultures only when they were supplemented with exogenous adenosine deaminase and allogeneic helper cells. A parallel study of T lymphocyte differentiation in vitro performed in fractionated bone marrow cells was suggestive of arrested differentiation at different steps along the differentiation pathway. In two patients with evidence of functional B cell precursors, deficiencies of helper T cell function could be attributed to differentiation defects at the level of the stem cells in one and the thymus in the other. The findings reported here further substantiate the heterogeneity of the severe combined immunodeficiency disease syndromes.

Activation of human peripheral blood lymphocytes: effect of concanavalin A and lipopolysaccharide on in vitro synthesis of DNA and immunoglobulins

We studied the interaction of lipopolysaccharide (LPS) and concanavalin A (Con A) with regard to IgM and IgG production in in vitro cultures of human peripheral blood lymphocytes (PBL). In our system LPS alone over a wide range of concentrations did not stimulate detectable IgM or IgG production, while Con A at optimal (6 microgram/ml) and suboptimal (0.6 microgram/ml) mitogenic concentrations induced synthesis of small amounts of Ig. A marked enhancing effect was present when both Con A and LPS were added to the cultures. The different doses of LPS has similar effects on both classes of Ig, and typical dose-response curves were obtained. To evaluate the cellular basis of this synergism, the effect on cell proliferation was studied under identical experimental conditions in normal subjects and patients with X-linked agammaglobulinaemia (X-LA). Parallel cultures were set up after monocyte depletion by adherence on Petri dishes. On day 3, increasing doses of LPS were associated with progressive decreases in 3H-thymidine (3H-TdR) incorporation. Similar results were obtained with normal lymphocytes and those from X-LA patients. Monocyte depletion did not substantially alter the lymphocyte response pattern. The preferential induction of helper activities, either directly by helper stimulation or indirectly by suppressor inhibition, is suggested as a possible mechanism of the interaction observed.

Characteristics of immunoglobulin secretion in man evaluated by a reverse hemolytic plaque assay

The kinetics of Pokeweed mitogen-induced transformation of human B-lymphocytes into immunoglobulin-secreting cells were examined in a reverse hemolytic plaque assay using protein A-coated sheep red blood cells as indicator cells. Peak responses occurred consistently after 6-8 days of incubation. After determination of the optimal experimental conditions the RHPA was found to be a reliable tool to estimate ISC in vitro; the technique was also found to be applicable for experiments surveying the B-cell response of an individual over a period of months. The PWM-induced transformation of B cells was absolutely T-cell-dependent. Other substances known as typical T-cell mitogens were also tested for polyclonal B-cell activation and some of them showed significant responses. Further experiments have shown that co-cultivation of non-HLA identical cells did not increase the number of plaques in unstimulated cultures whereas the addition of PWM leads to the generation of ISC within the expected range. These findings open a wide field of application of the RHPA in experimental and clinical immunology.

In vitro idiotypic suppression of chronic lymphocytic leukemia lymphocytes secreting monoclonal immunoglobulin M anti-sheep erythrocyte antibody

A patient with chronic lymphocytic leukemia was found to have B cells with surface immunoglobulin (Ig)M manifesting anti-sheep erythrocyte (SRBC) specificity together with a high titer serum monoclonal anti-SRBC IgM antibody. By immunizing a sheep with the monoclonal IgM antibody, followed by multiple absorptions against normal human IgM, an anti-idiotype (Id) antibody was obtained. The serum IgM anti-SRBC antibody was then demonstrated to share the same idiotypic determinants with the surface IgM with anti-SRBC specificity on the patient's B cells. The anti-Id antibody suppressed the spontaneous secretion of anti-SRBC antibody as well as the pokeweed mitogen-induced anti-SRBC antibody production as measured by a hemolysis-in-gel plaque-forming cell assay. In contrast, pokeweed mitogen-induced anti-SRBC plaque-forming cell responses of normal individuals were not suppressed by the anti-Id antibody. Thus, this study demonstrates in vitro suppression of human B-cell function by anti-Id antibody.

Activation of human B lymphocytes. XII. Differential effects of in vitro cyclophosphamide on human lymphocyte subpopulations involved in B-cell activation

The differential effects of in vitro cyclophosphamide (CY) on subpopulations of normal human peripheral blood lymphocytes involved in the pokeweed mitogen-induced plaque-forming cell (PFC) response against sheep red blood cells were examined. It was found that the plaque-forming B cells in this system are sensitive to CY over a wide concentration range including concentrations which have a minimal effect on overall cell viability. Kinetic experiments revealed that CY exerts its inhibitory effect on the PFC response only if added very early in culture. Thus, it appears that in vitro CY must exert its inhibitory influence on an early phase of polyclonal B-cell activation. When T-cell enriched (TCE) populations were incubated overnight with high concentration CY and then added back in co-culture to fresh autologous B cells, significant enhancement of PFC responses was observed suggesting a selective inhibition or elimination of a regulatory suppressor cell population found in TCE lymphocyte preparations. Helper T cells are relatively resistant to the inhibitory actions of CY. Thus, human B cells appear to be most sensitive to CY, followed in sensitivity by the suppressor cell populations in the T-cell fraction with relative resistance of the helper T cells. These observations have direct relevance in understanding the mechanisms of selective action of CY on normal human lymphocyte subpopulations with possible application to disease states in man.

Immunoregulation in Sjögren's syndrome: influence of serum factors on T-cell subpopulations

21 patients with Sjögren's syndrome (sicca syndrome) with either glandular or extraglandular involvement, but without other connective tissue diseases, were studied with regard to immunoregulatory T-cell subpopulations, B-cell function, and suppressor cell capabilities. Patients with isolated glandular disease as well as patients with extraglandular disease had normal absolute numbers of total lymphocytes, T cells, and B cells. However, 9 of 11 patients with extraglandular disease and only 3 of 10 patients with glandular disease had decreased relative proportions of T cells bearing receptors for the Fc portion of immunoglobulin (Ig)G (T(G)) which was explained by a factor that blocked the expression of the IgG Fc receptor on T(G) cells. This blockage was reversible since the factor could be removed by trypsinizing the T cells before T(G) determination. Serum from patients with abnormal proportions of T(G) cells, but not serum from patients with normal proportions of T(G) cells, blocked the expression of the IgG Fc receptor on normal T cells. The serum factor upon fractionation over Bio-Gel A 1.5 columns as well as over staphylococcal protein A-Sepharose 4B columns was found diffusely within the IgG fraction, and not in the IgM fraction. Neither patients with glandular nor patients with extraglandular disease manifested increased numbers of in vivo-activated circulating lymphocytes as determined by spontaneous anti-trinitrophenyl (TNP) plaque-forming cells (PFC). However, patients with glandular disease had reduced numbers of pokeweed mitogen-induced anti-sheep erythrocyte PFC (P < 0.01) as compared with normals and patients with glandular disease. Of note was the fact that despite the modulation of T(G) subpopulation by the serum factor in patients with extra-glandular disease, these patients manifested normal concanavalin A-generated suppressor cells of pokeweed mitogen-induced PFC responses in allogeneic co-cultures. This was unlike the suppressor cell defect previously described in this system with systemic lupus erythematosus patients. The discrepancy was attributed both to the fact that the T(G) defect was reversible and to the fact that concanavalin A-generated suppressor cells are not limited to the T(G) subset. Thus, these studies have demonstrated reversible abnormalities in T(G) cells in patients with extraglandular Sjögren's syndrome which are not associated with suppressor cell defects. The discrepancy between these findings and the immuno-regulatory defects demonstrated in systemic lupus erythematosus may explain the difference in severity of the autoimmune expression in these diseases.

Effect of rifampin on the immune response in mice

In an investigation of the effect of rifampin on the immune response in mice, the cellular immunity was evaluated with the split-heart allograft technique. The survival time of the heart in animals treated with rifampin at a dose of 20 mg/kg per day from the day of the transplantation until the graft was rejected was longer (33.7 days, P less than 0.001) than that of animals not treated with antibiotics (14.5 days). When rifampin was given at a dose of 5 mg/kg per day for the same period, the mean survival time of allografts was 19.5 days. The number of demonstrable plaques of hemolysis and the humoral antibodies to sheep erythrocytes were also reduced by a human therapeutic dose (20 mg/kg per day). However, the suppression of the humoral immune response was probably of more limited biological significane, suggesting a differential sensitivity to rifampin. In contrast to rifampin, benzylpenicillin had no noteworthy inhibiting effect on the cellular or humoral immune response.

Specific in vitro antibody response to influenza virus by human blood lymphocytes

Advances in understanding of human immune responses depend, for obvious reasons, on the use of in vitro techniques for culture of peripheral blood lymphocytes (PBL). We report here that specific antibody responses to influenza virus can readily be obtained using simple, reproducible methods. The system will be useful for the analysis of the cellular requirements for antibody production, the genetics of immune responsiveness and in clinical studies of immunosuppressed and immunodeficient patients.

Antibiotics and suppression of lymphocyte function in vitro

The effects on the mitogenic response of human T lymphocytes were studied for 20 different antibiotics. No apparent inhibitory effect could be detected for penicillins, cephalosporins, aminoglycosides, chloramphenicol, sulfamethoxazole, trimethoprim, nalidixic acid, and 5-fluorocytosine. There were effects at high concentrations with erythromycin, clindamycin, and rifampin, and these antibiotics could also be shown to depress the mitogenic response of B lymphocytes. With fusidic acid, nitrofurantoin, and doxycycline there was an inhibiting effect at low concentrations on the mitogenic responses of B and T lymphocytes and on in vitro antibody production. Protein synthesis in unstimulated lymphocytes was also inhibited. Some antibiotics thus may impair the function of human lymphocytes in vitro.

Evidence for the synthesis and release of strongly immunosuppressive, noncytotoxic substances by Streptococcus intermedius

Products secreted by Streptococcus intermedius were studied for their effects on the immune response. Three different preparations of crude extracellular products from S. intermedius (CEP-Si) were found to have powerful suppressor activity in vitro as shown by inhibition of human lymphocyte proliferation (uptake of [3H]thymidine) and protein synthesis in response to a wide variety of stimulants, including mitogens and antigens, and suppression of plaque formation by human cells in response to sheep erythrocytes. CEP-Si was noncytotoxic, because cells incubated with high concentrations of CEP-Si and subsequently washed were viable and recovered their ability to respond to mitogens, and because leukocyte migration was not inhibited by CEP-Si, nor was the release of leukocyte migration inhibitory factor from sensitized lymphocytes. The possibility of antigen or mitogen competition was excluded. The effects of CEP-Si in vitro were time dependent and did not require the presence of monocytes. Cells pretreated with CEP-Si and then washed suppressed plaque formation by fresh autologous cells in highly stimulated cultures. CEP-Si injected into C57BL/6 mice also strongly suppressed their immune response to sheep erythrocytes, and the in vivo suppression was correlated with the effects of CEP-Si in vitro.

Pokeweed mitogen induced differentiation of human B cells: evaluation by a protein A haemolytic plaque assay

Using the protein A plaque assay, the number of human cells secreting immunoglobulin of various classes after pokeweed mitogen stimulation was determined. At optimal response (on day 5-7) a mean of 58,354 IgM PFC/10(6), 34,207 IgG PFC/10(6) and 10,525 IgA PFC/10(6) cells was found when using peripheral blood lymphocytes. In spleen cells, peak values which were slightly higher than in blood, were obtained at day 4-6. The proportions of cells secreting light chains of either type were found to be comparable to those of unstimulated cells thus supporting the notion of the polyclonality of the response. Pokeweed mitogen stimulation of peripheral blood lymphocytes was found to be totally T-cell dependent whereas the response of spleen cells was not. When assayed for antigen-specific precursor cells in cultures stimulated by mitogen, the frequency of SRBC-specific IgM producing cells was found to be 1.3/1000 cells. This frequency was regularly found to be independent of medium supplement.

Lipopolysaccharide and lipid A-induced human blood lymphocyte activation as detected by a protein A plaque assay

Various purified cell wall lipopolysaccharides (LPS) from gram-negative bacteria and derivatives of these LPS were tested for their stimulatory capacity for human peripheral blood cells. Immunoglobulin (Ig) production was tested by an indirect plaque-forming cell assay using Staphylococcus aureus protein A-coupled erythrocytes and specific anti-Ig as developing serum. This method allows the detection of the majority of cells secreting Ig of a single class, and the number of plaque-forming cells detected are approximately 100-1000 times the amount obtained using normal sheep red cells as targets. LPS containing the O antigen-specific chain, as well as mutant products only containing lipid A and ketodeoxyoctonate trisaccharide, could induce cell division and antibody synthesis. The polypeptide antibiotic polymyxin B was found to inhibit LPS-induced activation. Furthermore, purified lipid A, complexed with bovine serum albumin, was also found to activate human peripheral blood B cells. These findings demonstrate that human peripheral blood lymphocytes can be activated by LPS and also indicate that lipid A is the active part of these molecules.

Activation of human B lymphocytes (the in vitro polyclonal B cell activator-induced plaque-forming cell system)

The characteristics of human B lymphocyte triggering, differentiation, and regulation are described using the polyclonally induced anti-sheep red blood cell hemolytic plaque-forming cell assay system. Technical and methodologic considerations, cellular requirements and mechanisms of regulation including suppressor and helper influences are discussed. Also considered are theoretical concepts regarding normal immune response versus pathologic immune states and the potential biologic role of polyclonal activation in these human immune mechanisms.