The influence of homogeneous cold agglutinins on polymorphonuclear and mononuclear phagocytes

The impact of individual clinical features in cold agglutinin disease: hemolytic versus non-hemolytic symptoms

INTRODUCTION

During the last decades, the pathogenesis of cold agglutinin disease (CAD) has been well elucidated and shown to be complex. Several documented or investigational therapies have been made available. This development has resulted in major therapeutic advances, but also in challenges in choice of therapy.

AREAS COVERED

In this review, we address each step in pathogenesis: bone marrow clonal lymphoproliferation, composition and effects of monoclonal cold agglutinin, non-complement mediated erythrocyte agglutination, complement-dependent hemolysis, and other effects of complement activation. We also discuss the heterogeneous clinical features and their relation to specific steps in pathogenesis, in particular with respect to the impact of complement involvement. CAD can be classified into three clinical phenotypes with consequences for established treatments as well as development of new therapies. Some promising future treatment approaches - beyond chemoimmunotherapy and complement inhibition - are reviewed.

EXPERT OPINION

The patient's individual clinical profile regarding complement involvement and hemolytic versus non-hemolytic features is important for the choice of treatment. Further development of treatment approaches is encouraged, and some candidate drugs are promising irrespective of clinical phenotype. Patients with CAD requiring therapy should be considered for inclusion in clinical trials.

New Insights in the Pathogenesis and Therapy of Cold Agglutinin-Mediated Autoimmune Hemolytic Anemia

Autoimmune hemolytic anemias mediated by cold agglutinins can be divided into cold agglutinin disease (CAD), which is a well-defined clinicopathologic entity and a clonal lymphoproliferative disorder, and secondary cold agglutinin syndrome (CAS), in which a similar picture of cold-hemolytic anemia occurs secondary to another distinct clinical disease. Thus, the pathogenesis in CAD is quite different from that of polyclonal autoimmune diseases such as warm-antibody AIHA. In both CAD and CAS, hemolysis is mediated by the classical complement pathway and therefore can result in generation of anaphylotoxins, such as complement split product 3a (C3a) and, to some extent, C5a. On the other hand, infection and inflammation can act as triggers and drivers of hemolysis, exemplified by exacerbation of CAD in situations with acute phase reaction and the role of specific infections (particularly Mycoplasma pneumoniae and Epstein-Barr virus) as causes of CAS. In this review, the putative mechanisms behind these phenomena will be explained along with other recent achievements in the understanding of pathogenesis in these disorders. Therapeutic approaches have been directed against the clonal lymphoproliferation in CAD or the underlying disease in CAS. Currently, novel targeted treatments, in particular complement-directed therapies, are also being rapidly developed and will be reviewed.

Clinical immunology of chronic cold agglutinin disease

We studied clinical and immunological characteristics of 15 patients with chronic cold agglutinin disease (CAD). Mean age at disease debut was 68 years for female and 67 years for male patients. The patients had no signs of other autoimmune diseases. All patients had V(H)4-34 encoded IgM kappa cold agglutinins (CA) in high titre. In five patients IgM increased significantly with advancing disease. Seven patients had reduced concentrations of lymphocytes, largely of CD4 and CD8 T cells. Percentages of NK cells (CD56) and B cells (CD19) were increased in seven and three patients, respectively. In six out of nine patients a clonal expansion of kappa positive B cells was found. Serum C3 was decreased in nine patients and C4 was decreased in 11 patients, six of whom had reduced CH50. Such data indicate that patients with CAD experience a continuous low-grade complement consumption. Five patients had experienced increased haemolysis during infections. After addition of active complement to patient sera in vitro, six sera showed increased haemolytic activity. Our results indicate that some patients with CAD have a relative deficit of complement in their serum and that an increase of complement production occurs during an acute phase reaction which enhances haemolysis. Our data also indicate that both CA titre and thermal amplitude are important characteristics when predicting complement activation and clinical course in CAD.

Comparison of group I and II soluble phospholipases A2 activities on phagocytic functions of human polymorphonuclear and mononuclear phagocytes

Soluble phospholipase A2 (PLA2) purified from rheumatoid synovial fluid (group II) and repurified Naja naja venom PLA2 (group I) were compared for their influence on phagocytic activity of human polymorphonuclear (PMN) and mononuclear (MO) phagocytes. Group II PLA2 reduced chemotaxis, adhesiveness, and intracellular bactericidal activity (ICBA) and induced release of muramidase from PMNs. Group I PLA2 suppressed chemotaxis, and enhanced ICBA but had no influence on other phagocytic functions. Group II PLA2 purified from synovial fluid or from placenta caused marked spontaneous superoxide generation followed by inhibition of phagocytosis-induced burst of energy. Group I Naja naja and porcine pancreatic PLA2 had no effect on superoxide generation. Group II but not group I PLA2 reduced markedly ICBA of monocytes. It may be concluded that human group II soluble PLA2, in concentrations comparable to those present in inflamed joints or in sera of patients with active arthritis or septic shock, causes spontaneous formation of the oxygen radical superoxide and release of lysosomal enzymes, and suppresses conventional phagocytic activities of PMNs and monocytes. Marked differences between group I and group II PLA2s may mean that these enzymes exert different influences on cell membrane.

Modulation of functional activity of human polymorphonuclear and mononuclear phagocytes by intravenous gamma globulin

Intravenous gamma-globulin was tested in a range of concentrations compatible with the increments obtained after therapeutic infusions for modulation of phagocytic functions of human polymorphonuclears (PMNs) and monocytes. Intravenous gammaglobulin in concentrations of 3.0 mg/ml or more increased adhesiveness and suppressed chemotaxis of PMNs. There was marked dose-dependent enhancement of opsonization of gram-positive and gram-negative microorganisms. Preincubation of PMNs with intravenous gamma-globulin caused enhancement of the total bacteria ingested, total bacteria killed, phagocytosis, and phagocytic index, when gram-positive and gram-negative bacteria were tested. During phagocytosis, there was no release of LDH or lysozyme; however, there was release of beta-glucuronidase. No significant difference in phagocytic enhancement was found when filtered and native intravenous gamma-globulin preparations were compared. There was marked enhancement of the superoxide anion generation by intravenous gamma-globulin above the concentration of 0.01 mg/ml. Intravenous gamma-globulin also markedly enhanced phagocytic activity of monocytes. Therefore, intravenous gamma-globulin modulates not only opsonization-related phenomena, but also exerts a complex influence on other aspects of phagocytic activity.

Influence of monoclonal IgM cold agglutinins on adhesiveness, phagocytosis, and bactericidal activity on human granulocytes and monocytes

Monoclonal IgM cold agglutinins (CA) bind and, in the presence of complement, are cytotoxic to various mammalian cells. The impact of these autoantibodies on functional capacity of phagocytes has not been studied until now. Herein we report that sera with monoclonal IgM anti-I and anti-i CA significantly reduce adhesiveness, phagocytosis, phagocytic index, and intracellular bactericidal activity of human peripheral blood polymorphonuclear cells (PMNs) at 37 degrees C and 24 degrees C. Anti-i CA were more active than anti-I. Sera with monoclonal IgMs without CA activity reduced the total number of ingested bacteria but otherwise had no effect on phagocytic functions. There was no difference in the degree of inhibition when anti-i and anti-I CA were tested against cord, maternal, and adult PMNs. Chromatographically purified a-I and a-i CA inhibited markedly phagocytosis in concentrations as low as 1 mg/ml. Phagocytic activity of peripheral blood monocytes was inhibited by CA at 18 degrees C but not at 24 degrees C or 37 degrees C. Pepsin digestion or reduction and alkylation of chromatographically pure IgM CA abolished completely their inhibitory activity. Thus, in physiological temperatures, monoclonal IgM cold agglutinins impair various phagocytic functions of human phagocytes. It may add to the susceptibility to infections in patients in which such autoantibodies are synthesized.

Cryptic cold agglutinin activity of monoclonal macroglobulins

One hundred and twenty sera with monoclonal immunoglobulin M's (IgM's) were tested for cryptic cold agglutinin activity against papain- and neuraminidase-treated adult and cord red blood cells (RBC). Fifteen sera (12.5%) agglutinated papain-treated RBC. Fourteen of these 15 sera also agglutinated neuraminidase-treated RBC. Ten additional sera agglutinated neuraminidase-treated but not papain-treated cells. Three patterns were observed among agglutinators of papain-treated RBC: either predominant agglutination of adult RBC, or of cord RBC or equal reaction, thus resembling I, i and non-Ii patterns of conventional cold agglutinins. We propose to call these patterns, tentatively, Icr (cr for cryptic), icr, and non-Iicr, respectively. Purified monoclonal IgM's retained the above patterns. Eluates from enzyme-treated cells contained monoclonal IgM's. Investigation of neuraminidase-treated RBC has shown that in distinction to T-anti-T system (Thomsen-Friedenreich receptor system), the majority of sera with monoclonal IgM's agglutinated more strongly adult RBC, and some agglutinated more strongly cord RBC. There was no loss of agglutinating activity after repeat freezing and thawing of the sera. Thus, it seems that monoclonal IgM's which react with neuraminidase-treated RBC detect antigenic determinants different from the T antigen. Cryptic CA activity of IgM's should be added to the list of antibody activities of these monoclonal immunoglobulins.

Monocyte (macrophage)-specific antibodies in patients with systemic lupus erythematosus (SLE)

Antibodies reactive for monocytes (macrophages) were found in the sera of patients with systemic lupus erythematosus (SLE). These antibodies were present in both IgG and IgM fractions and worked under both warm (37 degrees C) and cold (4 degrees C) conditions. These antibodies were specific for monocytes, because cytotoxic antibodies for monocytes were absorbed with monocytes, but not with T cells, B cells, and granulocytes. Furthermore, their specificity is also different from anti-HLA-DR antibody. The presence of these antibodies correlated with the activity of disease. They were found in 12 of 14 active SLE and 7 of 16 inactive SLE patients. The treatment of normal monocytes with these SLE sera and complement resulted in the depletion of their accessory function for T-cell activation and their phagocytic activity. In the previous paper, we reported that the accessory function of monocytes for T-cell activation was impaired in SLE patients. These results suggest that monocyte-specific antibodies play an important role in the pathogenesis of SLE through disturbing the monocyte regulatory function for immune responses.

Suppression of chemotactic activity of human polymorphonuclears by monoclonal IgMs with and without biological activity

The influence of monoclonal IgMs on migration of human polymorphonuclears was studied at various temperatures by the use of 19 sera with monoclonal IgMs from patients with macroglobulinemia of Waldenstrom (MW) without obvious biological activity, 29 sera with monoclonal IgM cold agglutinins (18 with anti-I and 11 with anti-i IgMs) and 3 sera with monoclonal IgM rheumatoid factor (RF). Under-agarose migration method and modified Boyden chamber method with double filters and 51Cr-PMNs were used. In under-agarose method, chemotactic differentials for controls, MW, anti-I, and anti-i groups were, respectively, 57 +/- 8 mm, 39 +/- 9 mm, 44 +/- 14 mm, and 32 +/- 16 mm at 37 degrees C and 47 +/- 18 mm, 22 +/- 11 mm, 17 +/- 9 mm, and 15 +/- 12 mm at 24 degrees C. All three sera with IgM RF inhibited chemotaxis. The differences between all groups and controls were significant at p less than 0.01. Random migration was inhibited at 24 degrees C (p less than 0.01) but not at 37 degrees C. Inhibitory concentrations of IgM in the sera tested were equal or less than 0.5 mg/ml. Thirteen sera were tested by the modified Boyden chamber method. At 37 degrees C 8 of 13 sera and at 24 degrees C 11 of 13 sera inhibited significantly chemotaxis at a concentration of IgM of 1 mg/ml. The lowest inhibitory concentration of IgM was 25 micrograms/ml. Eleven chromatographically pure IgMs were tested in the under-agarose assay. At concentrations of 0.4-3.7 mg/ml, eight IgMs inhibited chemotactic differential at 37 degrees C and nine inhibited it at 24 degrees C. At concentrations of 0.6-2.0 mg/ml, all seven pure IgMs tested by the Boyden chamber method significantly inhibited chemotaxis at 24 degrees C and 37 degrees C. Some IgMs inhibited chemotaxis at concentrations as low as 25 micrograms/ml. Ten IgM CA were eluted from the red blood cells. Eluates inhibited strongly chemotaxis at 24 degrees C and 37 degrees C. Heat inactivation did not alter inhibitory activity of IgM, however pepsin digestion or reduction and alkylation of purified IgMs did abolish their inhibitory activity. Inhibition of chemotaxis was not related to the light chain type, the titre, or the thermoamplitude of cold agglutination. However, monoclonal IgMs with anti-i cold agglutinin activity were stronger inhibitors than anti-I. Since 75% of IgMs tested inhibited chemotaxis at 37 degrees C, it is possible that monoclonal IgMs, especially those with anti-i cold agglutinin activity, inhibit PMN migration in vivo.

Status of major red cell blood group antigens on neutrophils, lymphocytes and monocytes

Previous investigators have reported that a number of red cell (RBC) antigens are found on neutrophils (PMN) and lymphocytes. However, there is a lack of consensus in the literature. Furthermore, few data are available concerning the occurrence of RBC antigens on monocytes. To address this problem, leucocyte fractions prepared from donors of known RBC antigen phenotype were analysed by fluorescence flow cytometry. Based on recent reports that PMN do not express ABH antigens and on the data presented here, the occurrence of major RBC antigens on leucocytes may be defined as follows: (1) lymphocytes express A, B. Lea and Leb antigens, depending on the ABH secretor (Se) status of the donor; (2) ABH and Lewis antigens cannot be detected on monocytes and PMN regardless of Se status; (3) D, E, e, C, c, Fya, Fyb, Fy5, Jka, Jkb, Jk, K, k, M, N, S, s, U, Vel, Coa, Lan, Jk3Yta, Dib, Ge, Sc:1 or Lub antigens were not detected on lymphocytes, monocytes and PMN; (4) lymphocytes, monocytes and PMN all express I, i, P and P1 antigens. The absence of selected Rhesus, Duffy, Kell, Kidd and other antigens on PMN is at variance with some previous reports. Furthermore, the distribution of RBC antigens on lymphocytes and monocytes has not been previously characterized using immunofluorescence flow cytometry.

Failure of histiocytosis X cells to express i blood group antigen

Expression of HLADR, I, i blood group antigen and T6 antigen were studied in Histiocytosis X cells and pulmonary alveolar macrophages using double labelling immunofluorescence technique or immuno-peroxidase procedure. Alveolar macrophages express simultaneously HLADR and i blood group antigen. Histiocytosis X cells, characterized by HLADR and T6 antigens, and by their ultra-structural marker do not express i antigen. These results confirm the hypothesis that histiocytosis X cells constitute a specialized sub-population of the mononuclear phagocyte system.

Modulation of locomotor activity of polymorphonuclear cells by cationic substances and cationic lysosomal fractions from human neutrophils

Seven cationic substances--human and egg-white lysozyme, RNase, protamine, histone, poly-L-lysine and poly-L-arginine; five cationic lysosomal fractions from human polymorphonuclears (PMNs); RNA; poly-L-glutamic acid; DNA; heparin; endotoxin; mastocytotropic agent compound 48/80; and cytochalasin B were tested for the influence on chemotaxis and random migration of human PMNs using under-agarose migration and Boyden chambers with two filters and [51Cr]PMNs. The above substances were either preincubated with PMNs, added to chemoattractants, or used instead of chemoattractants. In under-agarose migration method chemotaxis was inhibited by 11-35% when egg-white lysozyme, protamine, heparin, endotoxin, or compound 48/80 was added to the cells. High concentration of cytochalasin B inhibited chemotaxis by 73%. Cationic fractions I and V and low concentration of cytochalasin B enhanced chemotaxis by 11%, 41%, and 30%, respectively. When human and egg-white lysozyme, DNA, or cytochalasin B was added to the chemoattractants, motility of PMNs was inhibited. Cationic fractions II and V from human PMNs, when used as chemoattractants, enhanced cellular motility by 143-167%. Random migration was enhanced by heparin and inhibited by cytochalasin B and by cationic fractions from human PMNs. These findings suggest that various cationic and anionic substances and cationic fractions from human PMNs have heterogeneous influence on random migration and chemotactic activity of human PMN. Analysis relating chemotaxis to phagocytosis and to intracellular bactericidal activity (ICBA) has shown several patterns. Protamine, poly-L-lysine, poly-L-arginine, and agent compound 40/80 all inhibit chemotaxis and enhance phagocytosis and ICBA; cationic fractions II and V enhanced all three functions, whereas cytochalasin B suppressed phagocytosis and ICBA and had concentration-dependent modulatory influence on chemotaxis. It implies diverse mechanisms of action and possible impact on inflammatory reactions.

Blood group antigen expression in nephroblastoma

The histological distribution of A, B, H, Lewis, Pr, i and I blood group antigens (BGA) was studied in 19 nephroblastomas and one mesoblastic nephroma by means of the indirect immunofluorescence technique. In addition to general conclusions about the relatively limited BGA expression in the tumour cells, their histological distribution was found to be related to the differentiation level of these renal embryonic tumours. By comparison with normal embryonic, fetal and adult kidney it was shown that the nephroblastoma differentiation level is not higher than that of a 3-month fetal kidney. Furthermore, i antigen appears to be a non-specific marker of the histiocytic macrophage cells of the nephroblastoma stroma.

Biological activity of lymphocytotoxic antibodies in Graves' disease and Hashimoto's thyroiditis

Sera of 48 patients with Graves' disease (GD) and 23 with Hashimoto's thyroiditis (HT) were tested for lymphocytotoxic (LCT), granulocytotoxic (GCT) and monocytotoxic (MCT) activity. In GD, 12 patients (25%) had cold-reacting LCT and 13 patients (27%) had warm-reacting LCT. LCT were cytotoxic to both B and T cells but the majority of sera with cold-reacting LCT and eluates from lymphocytes were more cytotoxic to B lymphocytes. Warm-reacting LCT were directed exclusively against B cells. LCT did not correlate with peripheral lymphocyte counts, antithyroglobulin or antimicrosomal antibodies, sex, age, pregnancies, thyroid status or medication. However the mean duration of the disease was 15 months in LCT positive group and 55 months in LCT negative group (p less than 0.01). Weak GCT were found in 8 of 35 sera (23%). Six of 33 sera (18%) contained cold-reacting MCT and 9 (27%) had warm-reacting MCT. Some cytotoxins were directed against several types of cells as evidenced by cytotoxicity of eluates from lymphocytes against PMN and/or monocytes. Of 23 patients with HT, 11 (48%) had cold-reacting LCT. None had warm-reacting LCT. Sera and eluates from lymphocytes showed predominant cytotoxicity toward B cells. No correlation to the presence of antibodies, sex, age, pregnancies, thyroid status or medication was detected. Four of 23 sera had weak cold-reacting GCT, 5 had cold-reacting MCT which killed on average 31% of monocytes and 4 had weak warm-reacting MCT. Twelve of 22 sera from GD and HT had cytotoxic activity against thyroid cells (TCT). TCT correlated with LCT at p less than 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional characterization of the cells in chronic neutrophilic leukemia

Light and electron microscopy of neutrophils from chronic neutrophilic leukemia (CNL) did not reveal differences from normal mature neutrophils. However, functional characterization of CNL cells showed marked differences when compared to normal cells. CNL neutrophils were much less viable in suboptimal conditions. Their survival was further reduced by autologous serum and was corrected by normal human serm. CNL cells showed very active phagocytosis, but their bactericidal activity was reduced in suboptimal conditions. The total content of lysozyme and beta-glucuronidase was lower in CNL cells compared to normal neutrophils, but the release of these enzymes from stimulated cells was much higher than normal. This observation is compatible with a marked lysosomal lability. Cells from the patients' peripheral blood and bone marrow showed excessive growth in CFU-C assays. Marked susceptibility of CNL cells to cytotoxic activity of cold agglutinins, SLE sera, and CSFs was observed and may signify qualitative and/or quantitative differences in the membrane structure of CNL neutrophils, as compared to normal cells.

New antigenic determinant (Sa) on human lymphocytes and phagocytes

Presence of antigenic determinants reacting with homogeneous IgM/kappa cold agglutinin (CA) of a new specificity, tentatively called Sa, was investigated by bithermic cytotoxicity assay and by immunofluorescence. CA Sa killed on average 38% allogeneic peripheral blood lymphocytes (PBL) and up to 74% of autologous PBL. There was preferential kill of B-PBL compared to T-PBL. Some preference toward B cells was also noted using tonsillary B and T lymphocytes. Cytotoxic activity of CA Sa against chronic lymphocytic leukemia cells of B-type was almost equal to that of potent anti-I CA and much stronger than anti-i CA. Presence of additional B-cytotoxic factor in the serum was excluded by the use of red blood cell eluate composed solely of homogeneous CA. Thymocytes and helper-type T cells from a patient with T cell chronic lymphocytic leukemia were very susceptible to the cytotoxic action of Sa. CA Sa killed 39% of monocytes, but there was almost no kill of polymorphonuclear leukocytes. Lymphocytotoxicity of CA Sa was abolished by sialyllactose and was not influenced by I-active glycoproteins. Comparison of CA Sa to CA of other specificities showed marked differences, supporting the view that Sa has new, previously unrecognized specificity.

Expression of blood group I and i active carbohydrate sequences on cultured human and animal cell lines assessed by radioimmunoassays with monoclonal cold agglutinins

Human monoclonal anti-I and anti-i antibodies, reactive with known carbohydrate sequences, have been used as reagents to quantitate (by radioimmunoassay) and visualize (by immunofluorescence) the expression of the various blood group I and i antigenic determinants in a variety of cultured cell lines commonly used in laboratory investigations. It has been shown that the antigens they recognize are widely distributed on the surface of human and animal cell lines, expressed in varying amounts in different cell lines and on individual cells within a given cell line. In two cell lines, a transformation-associated increase in the expression of I antigen was observed. Because of their precise specificity for defined carbohydrate chain domains, these autoantibodies have become valuable reagents in biological chemistry.

Diagnosis of haematological disease using anti-i. II. Distinction between acute myeloblastic and acute lymphoblastic leukaemia

Leukaemic blast cells were obtained from the blood of six patients with acute lymphoblastic leukaemia (ALL) and 15 patients with acute myeloblastic leukaemia (AML). The blasts were compared with lymphocytes from normal subjects in cytotoxicity and 125I-labelled antibody binding tests using several examples of anti-i. As much i antigen was detected on ALL blasts as on normal lymphocytes; much less i antigen was detected on AML blasts. Studies of three patients with morphologically undifferentiated acute leukaemia suggest that, in tests with anti-i, blasts from such patients react either like lymphoblasts or myeloblasts despite the absence of the corresponding morphological features.

Diagnosis of haematological disease using anti-i. I. Disorders with lymphocytosis

Using cytotoxicity and antibody-binding tests, the i antigen was measured on the blood lymphocytes of normal subjects and of patients in whom a diagnosis of chronic lymphocytic leukemia (CLL) was considered because of a slight lymphocytosis in the blood and bone marrow. Among 25 patients, 15 had a normal amount of i antigen; in 10 there was a marked reduction in i antigen, such as is found in typical CLL. Similar studies were done on lymphocytes from 15 patients with clinical and morphological findings usually associated with lymphosarcoma cell leukemia (LSL). Nine had a normal amount of i antigen; in six there was a marked reduction of i antigen, suggesting a diagnosis of CLL. A study of the subsequent clinical course and final diagnosis in these patients suggests that the reduction in lymphocyte i antigen characteristic of typical CLL occurs in patients with early CLL who have only slight lymphocytosis, but not in patients with slight lymphocytosis from other causes. Similarly, a reduction in lymphocyte i antigen is found in patients with morphologically atypical CLL but not in patients with LSL.

Cell surface antigens detected on mature and leukemic granulocytic populations by cytotoxicity testing

Using a microcytotoxicity assay, the serological reactivity of human granulocytes, namely neutrophils and eosinophils, and chronic myeloid leukemia (CML) cells and cultured CML cell lines (K562, NALM-1) were examined. Mature granulocyte forms and cord granulocytes are readily lysed by specific granulocyte cytotoxins that do not react with random T and B lymphocytes, monocytes, red blood cells, or platelets. Furthermore, certain antisera were preferentially cytotoxic for eosinophil-enriched populations. Granulocytotoxin detected antigens on one of three CML blast cell populations tested and K562, but failed to react with NALM-1. By cytotoxicity, mature granulocytes were poor targets for B2-microglobulin and the appropriate HLA antisera although both sera types are absorbed with granulocytes. Furthermore, granulocytes did not possess B-lymphocytes (Ia-like) or blood group A, B, and Rh (D) antigens. Except for K562, both HLA and heterologous B-lymphocyte antisera were cytotoxic for the CML blast cell populations tested.

Monocyte-reactive antibodies in patients with systemic lupus erythematosus

Cold-reactive antibodies cytotoxic for peripheral monocytes from more than half of normal donors were found in the sera of 2 of 25 patients with systemic lupus erythematosus (SLE) and 1 of 26 with rheumatoid arthritis (RA), and they were absent in 25 normal sera. In contrast, lymphocytotoxic activity for T or B lymphocytes was found in over half of the lupus sera. The antibodies to monocytes were primarily IgM and exhibited varying specificities. Some of the antibodies were directed against antigenic determinants common to monocytes, T and B cells, or against determinants shared between monocytes and one lymphocyte type. One serum possessed a high titer of antibodies that were specific for monocytes. The clinical significance of antimonocyte antibodies remains to be established.

Actual aspects of cold agglutination

Cold agglutinins (CA) can be directed against antigens of the I/i system and the Pr complex. In addition, anti-Gd CA have been recently described. The CA immunoglobulins, serological specificities and the antigen immunochemistry are reviewed. CA permitted studies on interrelations between antibody structures and specificities. The significance of subgroup preferences and cross-idiotypic specificities is discussed. Interrelations between CA specificities and certain virus infections are pointed out, and recent results obtained from studies using CA as indicators for membrane alterations of other than red cells are reviewed.