Systemic lupus erythematosus complicated with cystitis, obstructive uropathy and intractable diarrhea: report of a case

A patient with systemic lupus erythematosus (SLE) displayed an unusual extraglomerular syndrome of cystitis with obstructive uropathy and severe secretory-type diarrhea. She had a history of idiopathic hypothyroidism and thrombocytopenia. The intractable diarrhea and cystitis with severe urinary obstruction regressed with large doses of systemic and intravesical corticosteroid therapy. The possibility of SLE should be considered fin any young female patient who has diarrhea of an unknown cause and cystitis.

Interferon production from peripheral blood, synovial fluid, and synovial tissue lymphocytes in patients with rheumatoid arthritis and ankylosing spondylitis

A previous study demonstrated that interferon was present in the serum of 30% of the patients with systemic lupus erythematosus (SLE), which was significantly higher than the 4.5% found in normal controls. We also recently reported that interferon production was deficient from SLE mononuclear cells, which has been attributed to immunodeficiency of the lymphocytes. In this study, interferon measurement included lymphocytes obtained from peripheral blood (PB), synovial fluid (SF) and synovial tissue (ST) in patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS). PB from normal subjects (NS) was used as a control. The results showed with PHA stimulation, that the interferon level in PBL (L = lymphocyte) in NS (70.0 +/- 67.5) was significantly higher when compared with PBL in RA (27.9 +/- 21.6). However, there was no difference between PBL in NS and AS. With ConA stimulation, the interferon level was significantly higher in the PBL of NS (130 +/- 59) and as compared with the PBL in RA (83.6 +/- 53.5). The SFL in RA (67.8 +/- 31.1) and the STL in RA (77.2 +/- 93.2) were also significantly different. It is concluded that interferon production was deficient not only in PBL in RA, but also in SF and STL in RA. The reduced interferon production from PB, SF and ST lymphocytes in RA patients may be due to previous release or immunodeficiency. Lymphocyte interferon production was normal in AS, which suggests that the lymphocyte abnormality between RA and AS may be different.

[The occurrence and clinical significance of antibodies to type II collagen in sera and synovial fluid of Chinese patients with rheumatoid arthritis]

Antibodies to type II collagen (Col II) in sera and synovial fluid (SF) were measured with an enzyme linked immunosorbent assay (ELISA) using a solid phase sandwich method. The subjects included: 42 patients with rheumatoid arthritis (RA); 31 cases of osteoarthritis (OA); 10 cases of gouty arthritis; 4 cases of ankylosing spondylitis (AS); 5 cases of systemic lupus erythematosus (SLE); and 44 normal controls. The antigens used to detect antibodies against Col II were in native and heat-treated denatured forms, both of which were purified from chicken sternal cartilage by limited enzyme digestion and differential precipitation with salt. The reactivity to native type II collagen was generally higher than the reaction to the denatured collagen. In sera, significant higher levels of Col II were detected in the different arthritis groups when compared with the normal control group, with the exception of AS. In SF, the Col II was significantly higher in RA than it was in OA (p less than 0.001), while no difference was present between gout and OA (p less than 0.05). When native Col II was simultaneously measured in sera and SF among arthritics, positive rates were both higher among RA (65% and 58%, respectively). Positive rates were only higher in sera among OA (59% in sera and 3% in SF) and were both lower among gouty arthritis. The above findings show that the measurement of Col II is more important in SF than in sera.

[The interrelationships of hepatitis B e antigen antibody and HBsAg-circulating immune complexes in asymptomatic HBsAg carriers]

The prevalence of asymptomatic HBsAg carriers and positive rate of HBsAg immune complexes (HBsAg-CICs) were comparatively higher among Chinese. The former is considered to be related with hepatitis B e antigen and the latter is not clear yet. In order to investigate the relationship between HBsAg-CICs and e antigen antibody among asymptomatic carriers. 90 subjects of carriers was tested for HBsAg-CICs by PEG-trypsinisation method and for e antigen antibody by radio-immunoassay. HBsAg-CICs were positive in 66 subjects among 90 carriers. The concentration of HBsAg-CICs (ng/ml) was significantly higher among 32 subjects with positive HBeAg (333.87 +/- 265.39) than 27 subjects with positive anti-HBe (181.03 +/- 162.05), p less than 0.02. Furthermore, the positive rate of e antigen and e antibody was just contrary among carriers with positive and negative HBsAg-CICs. Among 24 subjects with negative HBsAg-CICs, the percentage of positive HBeAg was much lower than positive e antibody. A significant interrelationship was present between positive or negative HBsAg-CICs and e antigen, antibody, the statistically significant was proved by the Chi square test. The above results showed that the high prevalence of asymptomatic HBsAg carriers among Chinese may be related to e antigen.

Cross-reaction of a monoclonal antibody to human MHC class II molecules with rabbit B cells

Monoclonal antibodies, 21w4 and 44H10, against human MHC class II determinants, were analysed for their reactivity with rabbit lymphoid cells. Both MAb bind to all human B lymphoblastoid lines, irrespective of their HLA-DR phenotype. HLA-DR antigens, purified by affinity to 21W4 IgG Sepharose, can be precipitated with 44H10 MAb, indicating that both antibodies react with the same molecules. Competitive inhibition studies with purified MAb IgG show that 44H10 and 21w4 recognize different epitopes of HLA-DR molecules. The 21w4 MAb, previously shown to cross-react with cells of pig, mouse and sheep, does not react with rabbit lymphoid cells. The 44H10 MAb binds to lymphoid cell suspensions prepared from rabbit appendix, spleen and mesenteric lymph nodes. Its reactivity correlates with that of RABELA, a polyclonal antibody specific for rabbit B cells. Mesenteric lymph node and spleen cell suspensions, depleted of sIg+ cells, are devoid of 44H10+ cells, while similarly-treated appendix B cells still contain a subset of B cells which are sIg-, RABELA+ and 44H10+. These studies thus report on the presence of MHC class II determinants on rabbit B cells, cross-reacting with human HLA-DR.

Fluorescence-activated cell sorter (FACS) analysis of rabbit cells

Monoclonal antibodies RB1, RB2, RT1, RT2 and RB3 were prepared against rabbit lymphoid cells by immunization with various fractions of rabbit lymphoid cells. The antigens detected by the antibodies are found on B and T cells in different densities. High proportions of polymorphonuclear and bone marrow cells which do not carry the RABELA and RTLA antigens carry the antigens of the RB and RT series. A subpopulation of appendix sIg-negative, RTLA-negative cells has a relatively high concentration of RT2. In general, B and T cells of the appendix show relatively small differences in the membrane densities of RB and RT antigens.

Immunoglobulin A nephropathy and ankylosing spondylitis. Report of two patients in Taiwan and review of the literature

We describe 2 patients with immunoglobulin A (IgA) nephropathy in association with ankylosing spondylitis. Renal biopsy demonstrated mesangial proliferative glomerulonephritis with prominent IgA, C3c, and less intense properdin deposition in the glomeruli. Intraglomerular clumps of virus-like particles were also observed in the kidney sample from one patient (case 2), who had an abnormal liver function. Our findings support the hypothesis that here is a possible common pathogenesis responsible for the concurrence of both IgA nephropathy and ankylosing spondylitis.

Computer software for specimen orientation adjustment using double-tilt or rotation holders

Computer software for specimen orientation adjustment relative to the incident electron beam has been developed. The difficulties encountered when tilting severely strained, highly beam-sensitive, or small-grain-size specimens with known structures using either a double-tilt or a rotation holder in transmission electron microscopy (TEM) can be minimized. Combined with computer programs for obtaining the reduced bases from diffraction patterns, the software is also useful for unknown crystals. The algorithm is introduced and examples are given.

Lymphokine-activated killer (LAK) cells: I. Age-dependent decline of LAK cell-mediated cytotoxicity

Experiments were designed to assess age-related changes in generation of lymphokine-activated killer (LAK) cells and to test whether these changes can be modified by diets differing in the proportion of polyunsaturated to saturated fatty acids (P/S). Ficoll-Hypaque-isolated spleen lymphocytes of rodent chow-fed, 6-85-week-old C57BL/6 (H-2b), 8-81-week-old C57BL/10 (H-2b) and 6-62-week-old SJL (H-2s) mice were cultured in IL-2-containing medium and examined in 51Cr cytotoxicity assay. Similarly, Ficoll-Hypaque-isolated spleen lymphocytes of 6-36-week-old SJL mice fed diets which differed in the ratio of polyunsaturated/saturated fatty acids were cultured in IL-2-containing medium and assayed for cytotoxicity. Age-related decline of LAK cell-mediated cytolysis was observed in mice of both H-2b and H-2s haplotype. The age-related decline of LAK cell-mediated cytolysis was the consequence of age-related decrease in the rate of LAK cell precursor maturation. SJL mice fed from birth with diets differing in P/S did not differ in LAK cell-mediated cytolysis.

[Specific circulating immune complexes in patients with hepatitis B]

Antigen specific hepatitis B surface antigen circulating immune complexes (HBsAg-CICs) were measured in 109 cases of hepatitis B with positive HBsAg (among them, 49 cases were acute and 60 cases were chronic hepatitis), 96 cases of asymptomatic hepatitis B surface antigen carriers, and 95 cases of normal blood donors. The mean concentration (ng/ml) of HBsAg-CICs was 303.50 +/- 357.70, 319.26 +/- 334.35 and 179.66 +/- 234.26 for the first three groups respectively; and was negative in normal groups. The concentration of HBsAg-CICs were significantly higher in acute and chronic group when compared with the asymptomatic carrier's group, (p less than 0.02 and p less than 0.01, respectively). Longitudinal series studies showed a close correlation between the levels or changes of HBsAg-CICs and the activity of the disease; patients with persistent HBsAg-CICs had a poor prognosis; and this were true not only in acute but also in chronic hepatitis patients. The mean concentration of HBsAg-CICs was higher in patients with positive hepatitis B e antigen (HBeAg) than in negative; but lower in patients with hepatitis B e anti-body (anti-HBe) positive than in negative. The higher prevalence of HBsAg-CICs in sera among asymptomatic HBsAg carriers in our study might be related to the prevalence of HBeAg among Chinese carriers. Further more, because HBsAg-CICs was related to the activity and prognosis of hepatitis B, it is worthwhile reconsidering whether so called "healthy" carriers were really healthy when their sera HBsAg-CICs tested positive.

Characterization of rabbit cells by monoclonal and polyclonal antibodies

Reagents for the identification of rabbit cell markers have been developed at a relatively slow rate. In this paper, rabbit cells are being characterized by polyclonal antibodies against a T-cell antigen (RTLA), a B-cell antigen (RABELA) and an analogue of murine Ia antigen. A number of monoclonal antibodies, specific for lymphocytes and/or bone marrow and/or polymorphonuclear leucocytes, have been used for the analysis of cells with identifiable membrane antigens. Populations that have cells with two of the above antigens in the membranes were identified. To these ends, complement-mediated cell kill by antisera alone and in mixtures was employed.

The rabbit immune system: cells regulating the proliferative response of purified T cells to concanavalin A and phytohaemagglutinin

T cell specific, B cell specific and Ia specific polyclonal antisera, as well as monoclonal antibodies, were employed to characterize cells involved in regulation of T cells, proliferating upon stimulation with concanavalin A or phytohaemagglutinin. Evidence for Ia+ accessory cells was obtained and the constellation of membrane antigens was determined by cytotoxic cell kill with the above mentioned antibodies. Help given by Ia+ cells was not blocked by polyclonal antibody against Ia, in the absence of complement. There was indirect evidence that a fraction of helper/accessory cells were Ia-.

Modification of a screening technique to evaluate systemic lupus erythematosus in a Chinese population in Taiwan

Several recent reports have suggested that systemic lupus erythematosus (SLE) may be more common in Chinese than in other populations. We have revised a validated questionnaire devised by Liang, et al, for use in Chinese and surveyed 1,836 people in a community survey and 2,000 students at a girls college in Taipei, Taiwan. This constitutes the largest population yet surveyed with this technique. Only 1 case of probable SLE was identified. Since many apparent normals gave the 3 positive responses suggested to require ANA screening, continued effort should be directed toward increasing survey specificity before the massive population surveys needed to calculate accurate prevalence.

Musculoskeletal manifestations in hemodialysis patients

One hundred and two consecutive patients receiving maintenance hemodialysis were interviewed and examined to analyze their musculoskeletal problems. Radiographic abnormalities of renal osteodystrophy were found in 23 and there were periarticular calcifications in 5. Only one patient had apatite associated knee arthritis and none had gout or calcium pyrophosphate deposition disease. Twenty patients had arthralgias, 3 polyarthritis, and 4 knee effusions all of which were incompletely explained. Correlations of arthralgias with radiographic findings was poor. Muscle cramps were seen in 24 patients, multiple fractures in one, symmetrical distal neuropathy in 18, and carpal tunnel syndrome in 9.

Clinical and pathologic studies of synovitis in polymyalgia rheumatica

Clinically detectable joint swelling was found in 10 of 13 fully evaluated patients considered to have polymyalgia rheumatica. Five patients had some joint findings at disease onset. Knees were most commonly affected. Sternoclavicular involvement was seen in 3 patients. Joint effusions in 8 patients had 300-5,700 leukocytes/mm3 with a mean of 2,900. Six synovial biopsy specimens studied by light microscopy revealed mild to moderate synovial proliferation and chronic inflammation that was generally less severe than in typical rheumatoid arthritis. Electron microscopy identified microvascular changes and large amounts of vesicular and granular debris in lining cells. In 1 patient, a "fingerprint" pattern in the granular material was suggestive of the findings in some immune complexes. This still unexplained synovitis may, as previously suggested, be important in the pathogenesis of the polymyalgia rheumatica syndrome.

T cell antigens and MHC determinants on rabbit granulocytes

A cell preparation, consisting of 90% granulocytes (polymorphonuclear leukocytes), can be obtained from the rabbit peritoneal cavity. These cells have some membrane antigens, similar to those characteristic of thymus cells (T1, T2), but they do not have the thymus antigen, RTLA. Unlike thymus cells, many polymorphonuclear leukocytes have Ia antigen, in their membranes. Heterogeneity of the cell population is indicated by differences in the number of cells affected by complement-mediated cytotoxic cell-kill with monoclonal antibodies, directed against T1 and T2 and with polyclonal antibodies directed against Ia.

A comparison of regulatory cells from rabbit spleen and appendix

Both spleen and appendix of the rabbit contain two types of accessory cells that regulate the response of T-cells to concanavalin A. These accessory cells are found among non-T, non-B adherent cells and among B-cells. There is, so far, no evidence for a sequential interaction of these two cell types. In addition, there is an inhibitory adherent cell type in the appendix that interferes with the B-cell-regulated proliferative T-cell response.

Rabbit spleen B lymphocytes as helper cells in lymphocyte activation by concanavalin A and phytohaemagglutinin

Using rosetting methods, we have purified rabbit B cells and studied their interactions with T cells purified by passage over an anti-immunoglobulin-coated Degalan beads column. B cells enhance the response of T cells to concanavalin A (Con A) and phytohaemagglutinin. In regulation of the response to Con A, an adherent cell is a third participating cell. B-cell preparation contain a minority of cells that can respond to T mitogens with the help of non-proliferating T cells, but the proportion of these responding cells is small, and the involvement of the T-cell impurity cannot be excluded.

Relative expression of light-chain allotypic specificities on the surface of rabbit lymphocytes as a function of age

Lymphoid cells of heterozygous Ab4/Ab9 rabbits of various ages were stained with fluorescent anti-allotype antibodies. In foetal and newborn rabbits, the percentage of Ab-positive cells in low; it increases with age, reaching the adult value when the animals are 100 days old. The rate of increase in the percentage of Ab4-positive cells is higher than in that of Ab9-positive cells. Thus, the Ab4/Ab9 ratio, which is initially 1, increases with age and reaches 2.2. in spleen and 4 in appendix of young adult animals. We conclude that the change in Ab4/Ab9 ratio is due to differential clonal expansion which we attribute to charge-related differences in the ability of Ab4 and Ab9 receptor-bearing cells to capture antigen when environmental antigens are encountered in postnatal life.

Rabbit B spleen lymphocytes and macrophages as accessory cells in T-cell activation by mitogens

The enhancement of the response of T cells to concanavalin A (ConA) and phtyohaemagglutinin (PHA) by macrophages has been shown in most species, whereas the accessory role of B cells has been only described in studies using human or rabbit lymphocytes. In rabbit, the accessory activity is confined to a subpopulation of B lymphocytes: the majority of B cells have sedimentation velocity of 2.5 to 4 mm/h, whereas the maximum of the accessory activity is found among the B cells, sedimenting with a velocity of 3.5 to 8 mm/h; B cells sedimenting between 1 and 3.5 mm/h have only a very weak accessory activity. Splenic adherent and/or phagocytic spleen cells may contribute additional augmentation of the response of T cells to ConA, since other macrophages (peritoneal and alveolar) are able to increase the ConA response to spleen T cells.

Isolation and characterization of a mouse-rabbit hybridoma

Immunoglobulin was obtained from a hybridoma cell line, which was a reclone of a hybrid between a rabbit cell and mouse myeloma cell (X63-Ag8). The immunoglobulin, isolated from the cell culture medium was found to be homogeneous by isoelectrofocusing and immunoelectrophoresis and consisted of mouse heavy and rabbit light chains, linked by disulphide bonds. All immunoglobulin molecules carried both mouse and rabbit determinants; mouse determinants were associated only with the heavy chains while rabbit determinants were only associated with the light chains. The rabbit light chains were of Ab4 allotypical specificity, but possess only some of the Ab4 determinants normally present in Ab4/Ab4 animals. It was suggested that the restriction in allotypical specificity may be a general property of light chain Ab allotypes; the normal serum immunoglobulins may be heterogeneous with respect to the allotypic determinants and any one molecule may possess only a proportion of determinants detected by a conventional anti-allotype antiserum.

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.

Rabbit B spleen lymphocytes and T helper cells. I. Responsiveness to mitogens of B cell subpopulations of different sedimentation velocities and subpopulations bearing or lacking Fcgamma receptors

The response to anti-allotype (anti-Ab4), Nocardia Water Soluble Mitogen (NWSM), pneumococcal polysaccharide type III (SSS III), and human Fc fragments of various purified and unfractionated rabbit spleen cell populations was determined in terms of 3H-thymidine up-take. B cells were isolated either from untreated suspensions of spleen cells or from suspensions from which adherent and phagocytic cells were removed. The purification factor was greater than the enhancement of 3H-thymidine uptake by anti-Ab4, NWSM, and SSS III as compared with the response of unfractionated spleen cells. It thus appears that a helper cell was involved: the mitogen response of purified B cells was enhanced by the addition of T cells. B subpopulations were separated by sedimentation or by rosetting, which allowed us to separate Fcgamma receptor-bearing cells from cells that did not possess this receptor. There were differences between cells responding to B mitogens not only in sedimentation velocity but also in the absolute number of cells. B cells bearing the Fcgamma receptor were less responsive to anti-Ab4 and more responsive to SSS III, NWSM, and human Fc than were B cells lacking the Fcgamma receptor.

Regulatory influences on the response of rabbit T cells to concanavalin A and phytohaemagglutinin

The proliferative response, induced in rabbit spleen cells by concanavalin A (Con A) and phytohaemagglutinin (PHA), is abolished when T cells are killed with antibody against rabbit thymus lymphocyte antigen (RTLA) in the presence of complement. The response was examined with purified spleen T cells, to which various helper cell fractions were added; it could be shown that B cells help the responding T cells. The helper effect in the response to PHA is abolished and the response to Con A is reduced by any manoeuvre which destroys or removes B cells. Help by B cells is given when helper cells have lost proliferative capacity as a consequence of mitomycin-C treatment. Spleen cells adhering to the walls of culture tubes help suspended T spleen cells in their response to Con A. This help could be abolished by complement mediated cell kill with antibody to rabbit bursal equivalent lymphocyte antigen (RABELA). On the other hand, the helper effect in Con A response was increased when T cells were removed. Thus the response of T cells to Con A is regulated by helper B cells and suppressor T cells.

Purification of rabbit B spleen cells by removal of adherent and of T cells

B lymphocytes from the rabbit spleen were freed of T cells by removal of cells which formed rosettes with papain-treated rabbit erythrocytes. Additional purification could be achieved if fractionation by rosette removal was preceded by removal with a magnet of cells which adhered to or ingested poly L-lysine coated iron core particles. Cell yield and purification were assessed by complement mediated cytotoxic kill of B and T cells with antibody directed against RABELA and RTLA, respectively. Other criteria depended on determination of the number of Fc receptor bearing cells and of thymidine uptake by cells which were stimulated with concanavalin A, PHA or with antibody directed against the allotypic specificity of receptor Ig light chains. Purified preparations of B cells were obtained in a yield of about 20% of the B cells in the original spleen and contained less than 10% of cells which were not B cells. This method allows purification which does not interfere with the membrane of the isolated cells.

Rabbit lymphoid cells. II. Anti-allotype antisera, lipopolysaccharide and other bacterial and fungal mitogens as probes for the identification of B-cell subpopulations

Removal of adherent cells or complement-mediated killing of rabbit thymus lymphocyte antigen (BTLA) bearing rabbit T lymphocytes did not abolish the responsiveness (increased thymidine incorporation) of lymphoid cells to antibody against immunoglobulin allotype, Nocardia water-soluble mitogen (NWSM), pneumococcal polysaccharide SIII (PPSIII), S. abortus lipopolysaccharide (LPS), lipid A conjugated to bovine serum albumin and a crude preparation containing C polysaccharide from the cell wall of Diplococcus pneumoniae. Isologous and heterologous antisera, directed against different portions of the Ig receptor, differed in their capacity to enhance thymidine incorporation. The difference in mitogenicity of these antisera was discussed in terms of the accessibility of cell-bound immunoglobulin receptor sites. Spleen cells, responsive to anti-allotype (Ab4) antiserum and B-cell mitogens, NWSM and PPSIII, were characterized by velocity sedimentation. The mean volume of NWSM- and PPSIII-responsive cells was larger than that of the cells responsive to anti-allotype antiserum. Fractionation of spleen cells on glass bead columns yielded a population of non-adherent cells which were two to six times as responsive to anti-Ab4 antiserum as the original spleen cell suspension. The responsiveness of peripheral blood lymphocytes to anti-Ab4 antiserum was significantly greater than that of spleen cells. On the other hand, spleen cells were more responsive to PPSIII than were cells from the peripheral blood, the popliteal and the mesenteric lymph nodes.

Rabbit lymphoid cells. I. T-cell mitogens, cell volume and adherence properties as probes for cellular heterogeneity

Thymus-derived cell populations were characterized by sedimentation velocity in the Earth's gravitational field, by adherence properties, and in terms of the thymus-specific antigen RTLA. T cells, responding to mitogens, could be shown to be a subpopulation of RTLA-bearing cells and to have a relatively large volume. The size distribution of mitogen-responsive cells from different individuals showed some variation, but in general large spleen cells took up less thymidine per 10(6) cells than did large cells from other lymphoid organs. Upon stimulation with concanavalin A (con A) small popliteal lymph node cells took up more thymidine per 10(6) cells than did small thymus cells. The corresponding small cells of mesenteric lymph node and spleen took up intermediate quantities of thymidine. Thymus-derived cells that were resistant to complement-mediated cell kill with RTLA antiserum showed greater responsiveness to con A than did the original cell preparations. Non-adherent cells incorporated more thymidine when stimulated with phytohaemagglutinin (PHA) than when they were stimulated with con A. Lightly adherent cells were relatively more responsive to con A stimulation and firmly adherent cells were less responsive to both. The findings were discussed in terms of the density of RTLA on the membranes of T cells. In adherence and in sedimentation velocity fractionation, the relative yield of nucleated cells always exceeded the yield of PHA- and con A-responsive cells. The differential separation of mitogen responsive and of co-operating cells were considered as a possible cause of this deficit.

Volume, adherence properties, membrane antigens and mitogen responsiveness of rabbit lymphoid cell subpopulations

Subpopulations of rabbit spleen cells which respond to T and B mitogens, respectively, can be distinguished by sedimentation velocity in the earth's gravitational field. T cell subpopulations which differed in their responsiveness to Con A and to PHA could be identified by differences in adherence properties and by their sensitivity to complement mediated cell kill with RTLA-antiserum.

Mitogen stimulation of rabbit spleen cells before and after complement-mediated cell kill with an antiserum directed against the thymus antigen RTLA

Rabbit thymus lymphocyte antigen (RTLA) has been previously characterized as an antigen of rabbit thymus-derived cells (Cell. Immunol<i>. 7: </i>484–501, 1973). It has now been shown that the antigen may be regarded as a thymus marker in terms of cellular responsiveness to various mitogens. It was found that only RTLA-bearing spleen cells responded to phytohaemagglutinin and concanavalin A with increased thymidine uptake. Only those spleen cells, which remained viable after treatment with RTLA antibody and complement, responded by thymidine incorporation to antibody against A4 light chain marker. The sensitivity of the detection of mitogen effects was improved by removing cells, adhering to or ingesting magnetic core particles, coated with poly-L-lysine. Following such pretreatment, there was a reduction in thymidine uptake by unstimulated spleen cells. This reduction in background thymidine incorporation made it possible to determine target specificity with mitogens of low potency. Using this technique, it became possible to demonstrate that lipopolysaccharide is a mitogen for rabbit B cells, albeit marginally so, and much less effective for rabbit than for murine B cells.

Cells as antigen carriers and as immunoglobulin producers. Synthesis of antibody and allogeneic immunoglobulin after transfer of antigen-treated cells to newborn rabbits

The injection into newborn rabbits of a small quantity of human albumin, associated with red blood corpuscles or nucleated rabbit cells, induces an antibody response in the majority of animals, whereas the same quantity of antigen in solution fails to stimulate antibody formation or induces tolerance. The promoting capacity of the cells depends on attachment of antigen to them. The antibody produced after the injection of albumin, associated with nucleated cells, is of recipient origin. However, immunoglobulin carrying the marker of donor cells can be demonstrated in the recipient animals, and may reach serum concentrations similar to those normally present in animals which are heterozygous with respect to the marker. It appears that the antibody-promoting function and the synthetic capacity for allotype are quite distinct and that the period required for allotype formation is very short with mononuclear peritoneal exudate cells and is very much longer with cells from the thymus. The capacity of cells from lymph nodes for sustained allotype formation is less than that of thymus cells but greater than that of mononuclear peritoneal exudate cells.