Enrichment in B cells after separation of lymphocytes from peripheral blood

Characterization of suppressor-inducer cells which control the production of rat erythrocyte-induced anti-erythrocyte autoantibodies

Mice immunized with rat erythrocytes produce autoantibodies to their own red blood cells, distinct anti-rat agglutinins and autoantigen-specific suppressor cells. Suppressor cells were detected by adoptive transfer of rat erythrocyte-immunized spleen cells to naive recipients. Such recipients failed to make erythrocyte autoantibodies after immunization with rat erythrocytes although their anti-rat erythrocyte response was unimpaired. Depletion and enrichment studies were performed to identify the cell type(s) which transfer suppression. B cell depletion of rat erythrocyte-immunized spleen cells by passage over Ig/anti-Ig-coated bead columns abrogated the transfer of suppression. However, suppression was still transferred after rat erythrocyte immunized spleen cells were passed over beads coated with a complex of 4-azido-2-nitrophenyl (NAP)-mouse IgG-rabbit IgG anti-NAP suggesting that T cells bearing Fc gamma receptors are not responsible for suppression. Positively selected B cells from rat erythrocyte-immunized spleen cells caused some suppression of erythrocyte autoantibodies but only after high numbers of cells were transferred. Neither positively selected Lyt-1+2- nor Lyt-1-2+ T cell subpopulations transferred suppression. By contrast, rat erythrocyte-immunized spleen cells which contained a mixture of B memory and T cells were suppressive and retained their suppressor activity after removal of Lyt-1-2+ but not Lyt-1+2- cells. It is proposed that these Lyt-1+2-T cells belong to a distinct population of suppressor-inducer cells which together with memory B cells stimulate the generation of effector T suppressor cells in naive recipients.

Functional differences between B cell-depletion techniques in removing memory B cells. Relevance to anti-erythrocyte autoantibody-specific suppressor cells

The efficiency of a number of B cell-depletion techniques was examined in a functional assay. CBA (Iga) mice were primed with rat erythrocytes and their spleen cells transferred, before and after B cell depletion, to mice of the allotype-congenic strain Igb. The recipients were challenged with rat erythrocytes and their anti-erythrocyte autoantibody response was measured together with the donor (Iga) and host (Igb) anti-rat erythrocyte antibody levels. Transferred unseparated cells suppressed erythrocyte autoantibodies and produced high levels of anti-rat erythrocyte antibodies. Transfer of panned, rosetted or nylon wool-passaged cells neither altered donor anti-rat erythrocyte antibody levels nor abrogated suppression. By contrast, passage of rat erythrocyte-primed B cells over Ig-anti-Ig-coated beads resulted in removal of donor rat-primed B cell activity and loss of suppressor cells. The B cell-depletion techniques were effective at removing B cells as judged by the reduced number of fluoresceinated anti-Ig-labeled cells among unbound cells although analysis on a fluorescein-activated cell sorter revealed that the most effective method was depletion on Ig-anti-Ig-coated beads. B cell depletion by panning removed the capacity of virgin but not primed cells to make adoptive antibody responses after transfer suggesting that the primed cells most efficient in adoptive transfer have a lower density of surface Ig than virgin cells. Treatment of donors with drugs which abrogated transferrable suppression of erythrocyte autoantibodies did not alter donor anti-rat erythrocyte antibody levels in recipients. It is considered that rat primed B cells are involved in the suppression of erythrocyte autoantibodies by acting as selective antigen-presenting cells for T suppressor inducer cells, rather than through an anti-rat erythrocyte antibody feedback mechanism.

The estimation of B lymphocytes and their subpopulations in pigs. A comparison between a method using whole blood and one using Ficoll-Paque purified mononuclear cells

This paper describes a simple method for determining the proportion of B lymphocytes and their subtypes in pigs, using washed whole blood. The method was compared with one using Ficoll-Paque purified mononuclear cells and was found to give significantly lower results (13.0 +/- 1.3% and 17.0 +/- 1.8%, mean +/- S.E., respectively). For 30 normal pigs, 13.9 +/- 6% (mean +/- S.D.) of lymphocytes in whole blood bore light chains and 12.1 +/- 5% bore IgM, while of lymphocytes in purified mononuclear cells, 17.0 +/- 6% bore light chains, 15.1 +/- 6% bore IgM, 1.4 +/- 1.4% bore IgG and 0.5 +/- 0.5% bore IgA.

The effect of temperature-dependent autorosettes on B/T cell ratios of purified rabbit peripheral blood lymphocytes

Contradictory reports as to B/T cell ratios in the peripheral blood lymphocytes (PBL) of rabbits led to an investigation of current purification methods. PBL prepared by sedimentation at 37 degrees C in gelatin solution showed the same B/T ratios as did whole blood. PBL prepared by the Ficoll-Hypaque method at 4 degrees C or at room temperature were enriched in B cells compared to the whole blood. This enrichment depended on the presence of autologous erythrocytes during centrifugation and it was not demonstrable when centrifugation was carried out at 37 degrees C. Resuspended red cell pellets contained more than 3 times as many rosette-forming cells if the pellets were obtained by centrifugation of blood on Ficoll at 4 degrees C rather than 37 degrees C. We, therefore, conclude that aggregation of T cells with autologous erythrocytes is responsible for the depletion of B cells in the PBL prepared by the Ficoll-Hypaque method at 4 degrees C or at room temperature.

Analysis of the lymphocyte distribution during Isopaque-Ficoll isolation of mononuclear cells from human peripheral blood

Using chromium-labelled mononuclear cells the movements of lymphocytes in Isopaque-Ficoll (I-F) gradients were analysed. Even small percentages of ox or autologous human erythrocytes mixed with the lymphocytes caused a significant loss of lymphoid cells and this loss was augmented when higher numbers of red cells were added. Such losses could be prevented using I-F gradients of higher densities, but then neutrophils and erythrocytes were found to contaminate the mononuclear suspensions recovered. Purified B and T lymphocytes were found to move identically on the gradients, but when human erythrocytes were added to the lymphocyte suspensions to be separated, a small but significant preferential loss of T cells was observed.

In-vitro reactions of lymphocytes in rheumatoid arthritis and other rheumatic diseases

Various lymphocyte functions and the percentage of different subpopulations have been measured in groups of patients with seropositive rheumatoid arthritis, seronegative ankylosing spondylitis, and psoriatic arthritis, Sjögren's syndrome, sicca complex, and in normal controls. Several abnormal results were found--in the responses to mitogens, in the antibody-dependent cytotoxic test, and in the percentages of EA rosettes (antibody sensitised chick red cells test) and surface immunoglobulin-bearing cells. In the light of these findings cytotoxicity and lymphocyte subpopulations were measured in further groups of rheumatoid arthritis patients in whom the disease was at different stages. The results showed that the changes in cytotoxic potential occurred in patients with active arthritis. Correlation tests showed significant positive associations between the percentage of SE rosette-forming cells (sheep red cells test) and the mitogenic responses to phytohaemagglutinin and concanavalin A, and between the percentage of EA rosette-forming cells and the levels of antibody-dependent cytotoxicity. The results are discussed in the light of our understanding of cellular subpopulations in the immune system.

Artefactual variations in the B and T subpopulations of rabbit blood lymphocytes depending on method of isolation, and blocking of C3 receptors due to in vitro activation of complement

Marked differences were found in the proportions of lymphocyte subpopulations in rabbit peripheral blood depending on the techniques used for the purification of lymphocytes. Rosette-forming reactions were used to find the numbers of T lymphocytes, Ig-bearing cells and cells with receptors for C3 or IgG-Fc. Some of the methods used for lymphocyte separation altered the relative numbers of T and B lymphocytes, through a disproportionate loss of T cells. Other changes were due to in vitro activation of complement detectable by the presence of C3 on the lymphocyte cell-membrane and causing partial blocking of C3 receptors. Highest yields of lymphocytes were obtained from defibrinated blood treated with carbonyl iron to remove phagocytes and methyl cellulose to sediment erythrocytes. This procedure was accompanied by in vitro activation of complement, with the consequences mentioned. Complement activation was inhibited by taking the blood into either EDTA or citrate. As EDTA was cytotoxic for rabbit T lymphocytes, citrate was considered best although the resulting lymphocyte suspensions were contaminated with up to 25% granulocytes and monocytes owing to the inhibition of carbonyl iron uptake by the prior exposure to citrate.

Isolation of lymphocyte subpopulations from rabbit peripheral blood. Comparison of methods based on recovery of rosette-forming cells and on recovery of Ig-bearing cells from a digestible immunoadsorbent

Two methods to obtain lymphocyte subpopulations, defined by specific surface receptors, from rabbit peripheral blood cells were compared as to cell recovery, yield and purity of the obtained fractions: a) the formation of rosettes between lymphocytes and SRBC or SRBC coated with an antigen--antibody--complement complex (D-SRBC), followed by isolation of the rosettes and recovery of the RFC, b) retention of surface-Ig bearing cells on an immunoadsorbent to which antibody to rabbit Ig was covalently attached via a digestible gelatin bridge, with subsequent recovery of the retained cells by the enzymatic digestion of the bridge. Purity of the isolated cell fractions was assessed in all cases by the percentage of cells staining with FITC-labeled goat anti-rabbit Ig. Using the rosette method, all of the RFC could be recovered from rosettes and a very pure, surface-Ig negative, sub-population of cells was obtained: however, the overall number of rosettes formed (SRBC and D-SRBC) was low (8-9% of the nucleated PBC). Very good recoveries and highly enriched cell populations were obtained with the digestible immunoadsorbent, provided certain precautions to minimize cell losses were taken. Thus, 47% of the input cells, representing 90% of the lymphocytes could be recovered; separated cell populations were 96% Ig-positive or, in another experiment, 96% Ig-negative.