Selective triggering of human T and B lymphocytes in vitro by polyclonal mitogens

Immunocompetent cells in man. IV. The inhibition of pokeweed mitogen-induced blastogenesis of normal human peripheral leukocytes by trypsin: a B-cell mitogen of mouse, but not of human, lymphocytes

Normal human peripheral blood lymphocytes were tested for their blastogenic response in vitro to trypsin. Although it has been shown by other investigators that mouse B lymphocytes are stimulated trypsin to undergo blastogenesis, we have shown that human lymphocytes are not stimulated by trypsin. Paradoxically, trypsin inhibits the response of human lymphocytes to pokeweed mitogen, a B-cell stimulat, without significantly affecting the response of these cells to phytohemagglutinin, a T-cell stimulant. These results serve to underline the functional dissimilarity of mouse spleen cells and human circulating lymphocytes, at least with respect to their blastogenic responses to mitogenic agents.

Cell-mediated immunity in the rheumatoid diseases. I. Skin testing and mitogenic responses in sero-negative arthritides

Cellular immunity has been investigated in patients with various kinds of sero-negative arthritis. The incidence of cutaneous response to recall antigen streptokinase-streptodornase (SK-SD), and the ability to mount a primary cutaneous response to dinitrochlorobenzene (DNCB) have been examined in patients with ankylosing spondylitis and psoriatic arthritis. The results were not significantly different from normal. In vitro lymphocyte transformation in the presence of phytohaemagglutinin (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM) has been measured using peripheral blood lymphocytes from patients with ankylosing spondylitis, psoriatic arthritis and Reiter's disease. In comparison with a control group, significantly reduced responses were found to a low dose of PHA in the ankylosing spondylitis and Reiter disease patients. Significant increase in response occurred to a high dose of PHA, in patients with psoriatic arthritis and Reiter's disease, and to PWM in Reiter's disease patients. The in vitro results in the ankylosing spondylitis, psoriatic arthritis and Reiter's disease patients suggest some abnormality in the T-cell population in sero-negative arthritis.

Mitogenicity of formalinized toxoids of staphylococcal enterotoxin B

Staphylococcal enterotoxin B is a potent mitogen for mouse and human lymphocytes. Mitogenic activity was retained after detoxification of the enterotoxin by formaldehyde at pH 5.0, 7.5, OR 9.5. The most active toxoid (pH 7.5) was separated into a monomeric, a dimeric, and a polymeric fraction (1 x 10(5) to 3 x 10(5) molecular weight) by gel filtration, and although each fraction demonstrated mitogenic activity, the polymeric fraction was clearly the most efficacious. These data show that mitogenicity of staphylococcal enterotoxin B does not depend on toxicity. This suggests that the mitogenic and toxic activities are effected by different sites on the molecule.

Migration inhibition of human leukocytes mixed with phytohemagglutinin-preincubated mononuclear leukocytes

An in vitro test able to demonstrate phytohemagglutinin (PHA)-induced migration inhibition of human peripheral blood leukocytes was investigated. The migration inhibition was demonstrated by the agarose migration technique. Purified mononuclear leukocytes which had been incubated for 30 min with PHA, then washed and added to non-separated leukocytes induced migration inhibition of the mixed cell population. Since no PHA was added to the non-separated leukocytes, a direct PHA effect on polymorph migration was avoided. If the PHA-preincubated mononuclear leukocytes were heated at 56 degrees C for 30 min, their ability to cause migration inhibition was abolished. This suggests that the inhibition was caused by migration inhibitory factor (MIF) produced by the PHA-stimulated lymphocytes.

Serum albumin is essential for in vitro growth of activated human lymphocytes

The effect of human plasma, the plasma protein fractions of Cohn, and crystallized serum albumin on the in vitro growth of human lymphocytes activated by concanavalin A (Con A) or bacterial lipopolysaccharide was compared. It was found that fraction V or serum albumin (SA) is essential for growth of activated T and B lymphocytes. The other plasma proteins have no effect. The growth response of Con A-activated T lymphocytes to increasing concentrations of SA is similar to the response to increasing equivalent concentrations of plasma suggesting but not proving that SA is the only growth-stimulating factor in plasma when added to a protein-free culture medium. The growth-promoting effect of SA is not due to the fatty acids or hormones bound to SA but is attributed to the albumin molecule itself or to a factor tightly bound to it. SA can also effectively replace plasma to stimulate proliferation of lymphocytes activated by allogeneic lymphocytes or purified protein derivative of tuberculin.

Immunocompetent cells from the lower respiratory tract of normal human lungs

Subpopulations of lymphocytes in the broncho-alveolar air spaces of normal human lungs were compared with those in peripheral blood. Bone marrow-derived (bursal-equivalent) cells (B cells) were identified by complement receptors (EAC rosettes) and by surface immunoglobulin. Thymus-derived lymphocytes (T cells) were identified by their proliferative response to mitogens and the E rosette technique. Cells in lung air spaces were recovered from eight healthy nonsmoking volunteers by segmental lavage with the flexible bronchofiberscope. On the average, macrophages constituted 78% and lymphocytes 17% of the cells in the aspirates. B cells detected by surface immunoglobulin and complement receptors equaled 22% and 15% of lung lymphocytes, respectively. The distribution of lung B cells into heavy chain immunoglobulin classes revealed IgM and IgG to be the predominant classes, with mean values of 14.5% and 9.3%, respectively; the corresponding value for IgA was 5%. A comparable order of frequency (IgM greater than IgG greater than IgA) was observed for purified peripheral blood lymphocytes in the same and other control subjects. T cells comprised the majority (47%) of identifiable lung lymphocytes by the E rosette method. The presence of lung T cells was also corroborated by their proliferative response to mitogens (phytohemagglutinin and concanavallin A), but the response was less than that of equal numbers of peripheral blood lymphocytes from the same subjects. The B/T cell ratio for lung lymphocytes was comparable to results with peripheral blood lymphocytes in the same subjects, but a higher proportion of lung lymphocytes could not be identified as either T or B cells. It is postulated that lung lymphocytes participate in the local immune defenses of the lung.

PHA stimulation of separated human lymphocyte populations

Lymphocyte preparations from peripheral blood and tonsils were separated into populations enriched with T or B cells by formation of rosettes with SRBC and separation of the rosette-forming and non-rosette-forming populations. T cell-enriched populations were also prepared by nylon column filtration. Using these methods preparations were obtained which comprised 80--95% T or B lymphocytes as determined by E-rosette formation and surface immunoglobulin (Ig) staining. PHA responsiveness, measured by [3H]thymidine incorporation, varied between relatively wide limits and was critically dependent on the degree of separation obtained. Relatively pure B-cell populations (less than 12% T cells) from blood and tonsils gave low PHA responses while preparations from blood still containing 24--38% T cells gave responses equal to or even greater than those of unseparated controls (60--78% T cells). T cell-enriched populations (80--86% T cells) responded to an equal or greater degree than controls but more efficient separation (greater than 90% T cells) resulted in markedly reduced stimulation. There was thus no simple correlation between the degree of phytomitogen-induced transformation and the number of T cells present. It is concluded that the low response of relatively pure T-cell populations may be due to depletion of B cells or non-lymphoid cells (or both) during the separation procedures. These observations have implications for the use of PHA stimulation as a measure of T-cell activity in mixed populations such as those of human peripheral blood leucocytes.

Expression of a receptor for IgM by human T cells in vitro

The capacity of human peripheral blood lymphocytes (PBL) to bind antigen-IgG antibody (EA(IgG)) and antigen-IgM antibody (EA(IgM)) complexes was investigated using a rosette technique with ox erythrocytes coated with rabbit IgG or IgM antibody. It was found that while EA(IgG)-rosette-forming cells (RFC) were detected on PBL freshly drawn from normal individuals, EA(IgM)-RFC were present only in suspensions kept in culture for 24 h in mediá supplemented with sera containing very low or no amounts of IgM. Experiments of simultaneous detection of EA(IgG)-RFC or EA(IgM)-RFC and other membrane markers for human T or B cells together with experiments on purified T or B cell populations indicated that EA(IgG)-RFC were formed by both T and B cells, while T cells only were capable of EA(IgM) rosette formation. The specificity of the receptors for IgG and IgM was determined by studying the inhibitory capacity of purified human IgM and IgG in the rosette assay. The receptor for IgG was inhibited by IgG and not by IgM, while the reverse was true for the receptor for IgM.

Blastogenesis of human lymphocytes by endotoxin

Lipopolysaccharides of S. typhimurium, S. enteritidis and E. coli at wide range of concentrations were used to induce blastogenesis in human and mouse (nude) lymphocytes. Human lymphocytes from peripheral blood showed positive response to at least one source of LPS (stimulation index of 2-9). The optimum concentration resulting in maximum stimulation varied with different individual, sources and concentrations of LPS used. Lymphocytes from cord blood failed to respond to LPS, but had positive response to PHA. All three LPS produced about equally strong mitogenic effects on mouse spleen cells.

Macrophage-lymphocyte clusters in the immune response to soluble protein antigen in vitro. II. Ultrastructure of clusters formed during the early response

Macrophage-lymphocyte clusters are formed when lymph node cells and autologous peritoneal exudate cells from guinea pigs immunized with tubercle bacilli are cultured in the presence of purified protein derivative of tuberculin (PPD) for 20 h. We have studied the ultrastructure of these clusters employing transmission and scanning electron microscopy. The most simple macrophage-lymphocyte cluster consisted of one macrophage, one large central lymphocyte with a blastoid appearance attached to the macrophage with a broad area of contact, and from a few to more than 20 small peripheral lymphocytes attached to the central lymphocyte by their uropods. Some clusters were of more complex type, containing two or three macrophages or one macrophage with more than one central lymphocyte attached to the surface, but even in these clusters each peripheral lymphocyte was attached only to one central lymphocyte. By morphological criteria the peripheral lymphocytes were T lymphocytes.