Cells and mediators involved in immunoglobulin synthesis by human circulating mononuclear cells. IV. B cells synthesize but do not secrete immunoglobulins because of a defect in the non-T non-B (null) cells

Null cells (non-T and non-B lymphocytes) have previously been demonstrated to be obligatory participants for immunoglobulin synthesis and secretion by normal B cells in culture. Normal null cells have been demonstrated to secrete a factor, human immunoglobulin synthesis/secretion-facilitating factor (HISFF), which can replace the null cells in the culture. In this investigation, the B cells of an 8-month-old male infant and a 46-year-old male adult who presented with a humoral (antibody) immunodeficiency syndrome synthesized immunoglobulin but did not secrete immunoglobulin after culture with pokeweed mitogen and autologous T cells, monocytes, and null cells. In contrast, the patients' B cells synthesized and secreted immunoglobulin after the addition of allogeneic normal null cells or HISFF to the cultures. The same results were obtained with the cells of the infant and the adult patient tested at monthly intervals for 4 months. The results demonstrate that the patients' T cells, B cells, and monocytes functioned normally and that only the patients' null cells were defective. These findings provide an explanation for the absence of immunoglobulin in the circulation of "non(immunoglobulin)secretors," although they possess normal numbers of circulating immunoglobulin-synthesizing B cells. The defect is in the null cell and not in the B cell and consists of the inability of the null cell to secrete HISFF that facilitates the synthesis and secretion of immunoglobulin by the B cell.

A non-cytotoxic suppressor of immunoglobulin synthesis and secretion by B cells of normal humans and patients with rheumatoid arthritis and systemic lupus erythematosus

A factor secreted by thymocytes of immunized rabbits totally suppressed both the initiation of, and ongoing synthesis and secretion of, lectin (PWM)-induced synthesis of IgM and IgG immunoglobulins by the circulating B lymphocytes of normal humans, and of twenty consecutive patients with rheumatoid arthritis and twelve consecutive patients with systemic lupus erythematosus. The suppressor factor, referred to as human Ig synthesis/secretion suppressor factor or HISSF, is not HLA restricted in its activity and is not cytotoxic to the circulating human mononuclear cells (B cells, T cells, Null cells and monocytes). It was demonstrated that T cells precultured with HISSF were transformed into suppressor cells which, when added to fresh cultures of autologous B cells, suppressed the synthesis and secretion of IgM and IgG. On the basis of its suppressive and non-cytotoxic properties in vitro, HISSF may be an effective immunosuppressant in the treatment of patients with autoimmune diseases.

Immunologic defects following trauma: a delay in immunoglobulin synthesis by cultured B cells following traumatic accidents but not elective surgery

The immune status of trauma patients was compared with that of elective surgery patients and normal controls. The trauma patients, the elective surgery patients, and the controls were all male, aged 18 to 36 years, in previous good health and with similar Injury Severity Scores. Only one of eight immunologic activities assayed distinguished between these groups of subjects. It was observed that the synthesis and secretion of immunoglobulins (Ig) in vitro by the circulating B cells of the trauma patients was markedly impaired when compared to Ig synthesis by B cells of the elective surgery patients or controls. Furthermore, it was demonstrated that the B cells, and not the T cells, Null cells, or monocytes, were defective in the trauma patients. The results indicate that diminished Ig synthesis and secretion by the circulating B cells of the trauma patients cannot be attributed to the surgery; rather, it appears that the defects in the B cells are a direct result of the trauma.

Cells and mediators which participate in immunoglobulin synthesis by human mononuclear cells. III. Null cells secrete a factor(s) (human immunoglobulin synthesis/secretion-facilitating factor) that can replace the null cells in the synthesis of immunoglobulin by cultured B cells

In the accompanying communication, it was demonstrated that the null cells, the TM cells, monocytes and PWM are all obligatory participants in the synthesis and secretion of immunoglobulins by human B cells in culture. Here we demonstrate that the null cells secrete a factor, referred to as human immunoglobulin synthesis/secretion-facilitating factor (HISFF) that can replace the null cells in the cultures. HISFF is distinct from the known T cell-derived interleukins. HISFF functions in an HLA-unrestricted fashion since it can facilitate the synthesis and secretion of immunoglobulins by allogeneic B cells. The null cells cultured with TM helper cells and PWM required monocytes in the culture in order to secrete HISFF. Furthermore, B cells cultured with TM cells in medium containing HISFF, monocyte-derived factors and PWM nevertheless required monocytes in order to respond to the HISFF signal. Thus, the monocyte plays a pivotal role in the secretion of and response to HISFF. Normal levels of immunoglobulin were synthesized even when HISFF was added to the cultures of B cells, TM cells and monocytes, in the presence of PWM, as late as day 6 of the 7 day culture. We conclude that the null cells participate in immunoglobulin synthesis by the B cells by secreting a soluble mediator, HISFF, capable of replacing the null cells in the culture; and that the HISFF signal is the last signal received by the B cell before it begins to synthesize and secrete immunoglobulins.

Cells and mediators which participate in immunoglobulin synthesis by human mononuclear cells. II. The mechanism of null cell participation in immunoglobulin synthesis and secretion by B cells

Immunoglobulins were synthesized and secreted by human B cells cultured with T cells with receptors for FcM (TM) helper cells, monocytes, null cells and PWM for 7 days. Immunoglobulin synthesis did not take place if the null cells were omitted from the cultures irrespective of the duration of the culture period. Null cells incorporated into the cultures at only 25% of their optimal concentration did not affect immunoglobulin synthesis markedly by the cultured B cells. However, the number of B cells in the culture could not be diluted without an accompanying marked reduction in immunoglobulin synthesis. The B cells synthesized and secreted significant quantities of immunoglobulin even when the null cells were added as late as day 6 of the 7-day culture whereas no or very little immunoglobulin was synthesized if the B cells were not present from the beginning of the 7-day culture. It was demonstrated that cultured null cells do not transform into B cells and do not attain their immunoglobulin-synthesizing function. Furthermore, cultured B cells do not transform into null cells and do not attain their helper function. The null cells can also be distinguished from the B cells on the basis of cell-surface markers, receptors, and blastogenic responsiveness to phytomitogens. It is concluded that (i) the human circulating B cells require the null cells, in addition to the TM cells, monocytes and PWM, in culture in order to synthesize and secrete immunoglobulin; (ii) the null cell signal that stimulates immunoglobulin synthesis and secretion by the B cells is probably the last signal following the TM helper cell, monocyte and PWM signals received by the B cells; and (iii) the null cells and the B cells constitute distinct lineages of cells.

Surface receptors and immune activity of purified human circulating mononuclear cells. V. Circulating null cells and a factor secreted by the null cells inhibit the synthesis of receptors for Fc mu by T cells in culture

Receptors for Fc mu (Fc mu R) were not detected on freshly isolated unfractionated circulating human mononuclear cells (MNC) or purified T cells. However, a significant percentage of the T cells (20% to 40%), but not of the unfractionated MNC, exhibited Fc mu receptors following culture for 24 h at 37 degrees C in medium enriched with fetal calf serum. These receptors were newly synthesized by the T cells since they were not detected on T cells cultured for 24 h with cycloheximide in a non-cytotoxic concentration. The absence of Fc mu R on the cultured unfractionated MNC (of which 70% are T cells) suggested that non-T cells within the MNC-B cells and/or null cells and/or monocytes suppressed the synthesis of Fc mu R by the T cells. These cells were individually assayed for their capacity to suppress Fc mu R synthesis by co-cultured T cells. The null cells were able to totally suppress Fc mu R synthesis whereas the B cells and monocytes exhibited no suppressive activity. Null cells cultured for 24 h at 37 degrees C secreted a factor which inhibited the synthesis of receptors for Fc mu by the cultured T cells. This factor is referred to as receptor synthesis suppressor factor or RSSF. On the basis of these findings, it is concluded that (a) the circulating T cells do not possess Fc mu R; these receptors are synthesized de novo by the T cells in culture, (b) the null cells, but neither the B cells nor the monocytes, suppress the synthesis of the Fc mu R by the T cells and (c) the null cells, but neither the B cells nor the monocytes, secrete a factor, receptor synthesis suppressor factor, which can suppress the synthesis of Fc mu R by the T cells.

Cells involved in the immune response. XXXVI. The thymic antigen-specific suppressor cell in the immunized rabbit is a T cell with receptors for FcG and the antigen and it acts, via a secreted suppressor factor, directly on the immune splenic AFC B cell to inhibit antibody secretion

Following i.v. immunization of the normal outbred rabbit with sheep (SRBC) or horse (HRBC) erythrocytes, antigen-specific suppressor cells are generated in the thymus capable of inhibiting the generation of haemolytic plaques by the autologous or allogeneic splenic antibody-forming cells (AFC) in the plaque-forming cell (PFC) assay. These suppressor cells secrete an antigen-specific suppressor factor in short-term (4-24 hr) culture in vitro. The suppressor cells are not detected in the thymus prior to Day 4, exhibit peak activity between Days 5 and 11 post-immunization, and decline slowly thereafter. Suppressor cells can no longer be detected in the thymus by Day 60 postimmunization. Suppressor cells are not detected in any of the other lymphoid organs of the immunized rabbit nor in any lymphoid organ in the unimmunized rabbit. The thymic suppressor cell is a T cell with surface receptors for the antigen (SRBC or HRBC) and for FcG. On the other hand, the AFC B cells generated in the spleen of the immunized rabbit possess cell-surface receptors for only the antigen and not for FcG. Both the suppressor cells and the secreted suppressor factor act directly on the AFC B lymphocytes to inhibit the generation of antigen-specific haemolytic plaques in the PFC assay.

Cells and mediators which participate in immunoglobulin synthesis by human mononuclear cells. I. The obligatory requirement of null lymphocytes in the synthesis of immunoglobulins in vitro

The circulating mononuclear cells of normal adult human volunteers were fractionated into T and non-T lymphocytes. The T cells were then fractionated into TM and non-TM cells and the non-T cells were further fractionated, by both positive and negative isolation, into B cells and null cells. Culture of non-T cells, TM cells, and PWM for 7 to 8 days resulted in cytoplasmic Ig (cIg) synthesis by all B cells, as detected by immunofluorescence. However, culture of either purified B or null cells with TM cells and PWM resulted in a marked reduction (75%) of cIg-synthesizing cells. The addition of monocytes did not enhance cIg synthesis. Culture of reconstituted B and null cells with TM cells and PWM restored the capacity to synthesize cIg to the cells. It is concluded that null cells are required, as well as TM cells and PWM, for cIg synthesis by B cells.

Quantitative and qualitative impairment of immunoregulatory cells in the circulation of rheumatoid arthritic patients

T cells bearing receptors for the Fc portion of IgM or IgG, TM or TG cells respectively, in the peripheral blood of RA and OA patients were found significantly less often when compared with TM and TG cells in the peripheral blood of normal donors. Using culture combinations of TM, TG and B cells, we were able to demonstrate that the B cells in the peripheral blood of RA patients were constantly of low functional competence and the TMcells varied between highly competent and low competent. RATG cells in general suppressed normal B-lymphoblast differentiation.

Surface receptors and immune activity of purified human circulating mononuclear cells. IV. The demonstration of seven subclasses of T cells in the circulation of the normal individual: the cytotoxic activities of these cells

T lymphocytes were isolated from monocyte-depleted mononuclear cells of normal individuals by rosetting them with sheep erythrocytes. These purified T cells were preferentially depleted of cells with receptors for FcG (TG cells), FcM (TM cells), or C'3 (TC cells) by rosette formation with EA(G), EA(M), and EAC, respectively, before or after incubation for 24 hr in medium 199 fortified with fetal calf serum (20%). The unfractionated lymphocytes and the purified and the depleted T cells were analyzed for receptors to FcG, FcM, and C'3 and for cytotoxic activity in the natural killer (NK), antibody dependent cell-mediated cytotoxicity (ADCC), and mitogen-induced cell-mediated cytotoxicity (MICC) assays. The TG and TC cells were detected among the freshly isolated T cells, whereas the TM cells were detected only following 24 hr of incubation. Removal of TC cells from the 24-hr-cultured T cells resulted in removal of all the TC cells and in the concomitant removal of the majority of TM cells. Similarly, removal of TM cells from the 24-hr-cultured T cells resulted in the elimination of all TM cells as well as the majority of TC cells. These results demonstrate the in vitro generation of T cells with receptors for both FcM and C'3 (TM+C cells). Ten percent of the freshly isolated TG cells possessed detectable receptors for C'3 and/or FcM. These cells constitute the TG+C and TG+M lymphocytes. Support for consideration of these receptor-bearing cells as unique and stable cells is provided by the finding that TM and TC cells maintained in culture for up to 72 hr do not generate other receptors but retain the single receptor which characterizes each of these cells. Only a small percentage of cultured TG cells generate receptors for C'3 and FcM. It may therefore be concluded that the TG, TM, and TC cells are stable unireceptor-bearing cells. The TG, TM, TC, TG+C, TG+M, and TM+C lymphocytes account for approximately 50% of the circulating lymphocytes. Whether the remaining cells, the T null or TN cells, constitute the precursors for any or all of the receptor-bearing T cells remains to be determined. Unfractionated freshly isolated T cells were highly cytotoxic in the NK and PWM-mediated MICC assays but were relatively inactive in the ADCC, naturally occurring cell-mediated cytotoxicity (NOCC), and PHA- and Con-A-mediated MICC assays.(ABSTRACT TRUNCATED AT 400 WORDS)