Diagnostic immunology最新文献

Acquired immunodeficiency syndrome (AIDS), lymphadenopathy syndrome (LAS), and immune thrombocytopenic purpura (ITP) specimens were tested by an enzyme-linked immunosorbent assay (ELISA) for immunoglobulin (Ig) bound to platelets. All specimen evaluations were performed with General Diagnostic's newly developed kit procedure. The test measured but did not distinguish immune complex (IC) binding with platelet Fc receptor sites from platelet-specific antibody (PAb) binding with platelet antigen Fab-binding sites. Alkaline phosphatase-labeled antihuman IgG as conjugate detected IgG as low as 2.0 ng/ml or platelet-adsorbed, heat-aggregated IgG, simulating IC, at 2-10 ng/ml. There was a high prevalence of platelet-bound Ig in AIDS specimens (25/25) compared with normals (2/15), detected primarily by the indirect ELISA (p less than 0.001), and a preponderance of PAb in ITP specimens (5/5) compared with normals (6/22), by the direct ELISA (p less than 0.01). AIDS specimens had a geometric mean titer (GMT) of 173 ng of IgG bound/10(7) platelets, compared with the Ig from ITP, which had a GMT of 20 (p less than .0002). Monoclonal antibody to human receptors for IgG Fc fragment (anti Fc gamma R) inhibited 69% of specimens tested as having platelet-bindable antibody. Thus, the ELISA procedure would be useful in assessing but not in differentiating platelet-bound Ig in patients with AIDS and ITP and certain other clinical groups tested.

Complement activation occurs in many pathological conditions. Assays to evaluate the presence and extent of this activation may be limited by being qualitative, time-consuming, or radioactive. We have recently devised an enzyme-linked immunoassay that quantitatively measures the presence of the complement activation product C3d in plasma. The assay is rapid: Results can be available within 8 hours of submission. Intra-assay variation was low (4.9%) as was interassay variability (8.7%). This assay was then used to demonstrate that patients with systemic lupus erythematosus (SLE) have increased levels of circulating C3d as compared to those of normals (p less than 0.001). This assay may be useful to demonstrate continuing complement activation and inflammation in patients, even those without clinical symptoms.

Hematopathologists sometimes rely upon the "monoclonality" of immunoglobulin light chains of B-cells as an indicator of malignancy in lymph node biopsies. The validity of using the ratio of kappa to lambda light chains for defining monoclonality has not been statistically established, however. We examined with flow cytometry 57 unequivocal B-cell lymphomas and 49 benign lymphoid hyperplasias. Our purpose was to define and study the optimal numerical criteria for discriminating between B-cell lymphomas and benign hyperplasia on the basis of the kappa:lambda ratio. The data indicate that ratios less than .7 or greater than 5.5 are the optimum for discriminating between lymphoma and benign hyperplasia, but they have a false negative rate of approximately 27% and a 6% false positive rate. The reasons for the relatively low sensitivity are discussed. We conclude that kappa:lambda ratios are a fairly specific but insensitive parameter for distinguishing between B-cell lymphoma and benign lymphoid hyperplasia.

The LeucoPREP tube, a new method for separating mononuclear cells from whole blood, is described. The LeucoPREP tube is a 7-ml glass tube which contains a polyester gel and a solution of a sucrose polymer and sodium diatrizoate (Histopaque, Sigma). Platelets, lymphocytes, and monocytes are separated from granulocytes and erythrocytes based on differences in density. Platelets are then removed from the mononuclear cells by washing. The yield, viability, and percentage of various cell subpopulations obtained from the LeucoPREP tube are equivalent to those obtained from standard Ficoll-based methods. However, the LeucoPREP tube is a faster, less technically demanding method than Ficoll. The major advantages of the LeucoPREP tube are that 1) whole blood is added directly into the tube, unlike Ficoll methods, in which the blood must be diluted and carefully layered; and 2) it requires a very short (10 min) centrifugation time. The LeucoPREP tube should be highly desirable to anyone processing many blood samples, for example, clinical laboratories.

Antibodies against the human T-leukemia virus III (HTLV III) were detected by immunofluorescence in the sera of 17 out of 48 hemophiliacs (35.4%) without AIDS or ARC, frozen in 1983-84. Immunological data collected at that time were re-evaluated by separating HTLV III-positive and negative subjects. HTLV III positive patients had significantly reduced OKT4 cells (both in %: 26.1 +/- 10.9 vs 41.2 +/- 15.2; P less than 0.01; and in absolute numbers: 469 +/- 291 vs 1,038 +/- 541; P less than 0.005) and OKT3 lymphocytes (in absolute numbers: 1,234 +/- 550 vs 2,050 +/- 1,067; P less than 0.01). Subpopulations identified by other monoclonal reagents (OKT8, Leu 7, OKM1, anti-Tac) showed no significant differences between the two groups. Patients subsequently found to be seropositive had significantly more frequent anergy to skin tests to recall antigens and often an impairment of in vitro response to phytohemagglutinin A. Despite these relevant defects of some tests of cell-mediated immunity, in HTLV III-positive cases no clinical progression toward AIDS-related complex was observed in a mean period of follow-up of more than 1.5 years.

Glycogen-induced guinea pig polymorphonuclear leukocytes (PMNs) were employed in experiments designed to establish the optimal conditions for casein-stimulated chemotaxis. Subsequently, it was shown that guinea pig PMNs, in a serum-free medium, were susceptible to inhibition of migration by three distinct types of cell-directed inhibitors of chemotaxis found in normal or diseased human sera. Comparison of inhibition of migration of both guinea pig and human peripheral PMNs showed that guinea pig and human PMNs were equally susceptible to inhibition by sera from trauma victims; this inhibitor had a molecular weight of about 10,000 d. Human PMNs were slightly more susceptible than were guinea pig PMNs to inhibition of migration by a approximately 110,000-d inhibitor found in normal human sera. On the other hand, guinea pig PMNs were somewhat more susceptible to inhibition of migration by a approximately 400,000-d inhibitor of chemotaxis that was analogous to the inhibitor found in anergic serum. This information shows that guinea pig PMNs, in a serum-free medium, may be substituted for human cells in quantitative assays for these human serum factors.

Significant progress has been made in defining the clinical features, immunologic defects, and etiologic agent(s) of the acquired immune deficiency syndrome (AIDS) and its related disorders, but much remains to be learned about the natural history and pathogenesis of these diseases. Most immunologic studies to date have used peripheral blood lymphocytes or sections of lymph nodes for analysis. In this study lymph node cell suspensions from 37 patients with the persistent generalized lymphadenopathy syndrome (PGL) were phenotyped with monoclonal antibodies and flow cytometry and the results were compared with nodal suspensions from 49 patients with other types of reactive hyperplasia. Several significant differences were noted in the PGL nodes, including a decreased but not reversed T4/T8 ratio (1.44 vs 3.0, P less than 0.0001), a decreased percentage of T4+ lymphocytes, an elevation of T8+ lymphocytes, and increased numbers of activated lymphocytes. The shift in the T4/T8 ratio in PGL nodal suspensions was due primarily to a decrease in T4+ lymphocytes rather than in increase in T8+ cells. The possible specificity of these findings for infection by the AIDS agent and their potential prognostic utility are discussed.

Magnetically responsive albumin/protein A immunomicrospheres (MIMS) were prepared by reacting a mixture of albumin, iron oxide, and protein A in a two-phase emulsion coagulation procedure. The protein A ligand permits strong affinity binding of the monoclonal anti-HLA BW6 antibody to the 500-nm MIMS in a one-step process. HLA BW6+ and BW4+ human peripheral blood lymphocytes and mixtures of both were incubated with these MIMS. The findings obtained after only one run in a magnetic field were as follows: depletion of 98.6 +/- 0.9% of the target cells when 2 mg MIMS/10(6) cells were used, unspecific trapping of 5.9 +/- 2.5% of the nontarget cells from cell mixtures, and effective separation of cell populations as small as 1-0.1%. Thus, using albumin/protein A MIMS, the magnetic cell separation technique is simple, rapid, and highly sensitive.

Assays were performed on cells from 38 consecutive malignancies for both terminal deoxynucleotidyl transferase (TdT) and common acute lymphoblastic leukemia antigen (CALLA). TdT and CALLA occurred together only on lymphoblasts from some cases of acute lymphoblastic leukemia (ALL). In other cases of ALL, chronic myelogenous leukemia (CML) in blast crisis, and acute undifferentiated leukemia (AUL), TdT was expressed, but CALLA was absent. TdT was present predominantly on cells from the lymphoid lineage as proven by special histologic stains, and CALLA marked a population with a favorable prognosis. Significant discrepancies in the expression of these two markers and the unique properties of each suggest that both markers are useful for the full characterization of specific hematologic malignancies.