Diagnostic immunology最新文献

An indirect immunoenzyme (IIE) kit to detect autoantibodies in the sera of patients with systemic rheumatic diseases has been evaluated and compared to a conventional indirect immunofluorescence (IIF) assay. Both IIF and IIE were performed on a human epithelial cell line (HEp-2) using sera categorized on the basis of their autoantibody specificity. The correlation coefficient between the two assays was greater than 0.77 for all autoantibodies except antimitochondrial antibodies, which had higher end-point titers with the IIE kit. The inter- and intratest variability of IIE and IIF was comparable, differing by no more than one tube dilution. The IIE test had less background staining, allowing for better resolution and easier interpretation of staining patterns. IIE assay in the form of a commercially available kit is a reliable alternative to IIF.

Salivary IgA (SlgA) levels were determined in 1,539 normal children, aged between 8 months and 6 years. In four children (0.26%), an absence and in 25 children (1.62%) a relative defect, (less than 1 mg/dl) were found. These values are similar to those encountered in an adult male population. Conversely, the mean SlgA in all age groups we examined was much lower in comparison to the adult mean. This difference is particularly great for SlgA and much smaller for total salivary proteins. There was no difference between males and females, and no relation with personal or familial history of allergic and/or infectious episodes. The conclusions of this study are as follows: Absolute and relative SlgA defects, when found, are present from birth, The complete maturation of SlgA occurs after 6 years of age, The role of SlgA in the protection against allergic or infectious episodes perhaps ought to be revised.

Acquired immunodeficiency syndrome (AIDS) in childhood is characterized by recurrent bacterial infections, a feature common in antibody deficiency disorders. The present study was aimed at investigating B lymphocyte function in 15 children aged 6 months to 6 years with AIDS or AIDS-related complex (ARC). Spontaneous secretion of immunoglobulins by freshly isolated peripheral blood B cells and the generation of immunoglobulin and antibody-secreting cells in lymphocyte cultures after polyclonal and antigenic stimulation were quantified in hemolytic plaque assays. Despite excessive spontaneous immunoglobulin secretion, responses elicited by B cells after in vitro stimulation were depressed in these children. Responses to T-dependent as well as to T-independent stimuli were affected. Studies of immunoregulatory T cells and intrinsic B cell function suggested that deficient precursor B cells and abnormal immunoregulation contributed to the defects in B cell differentiation. These findings indicate that B lymphocyte dysfunction is an integral feature of HTLV III infection in children who clinically present as either AIDS or AIDS-related complex.

Serum levels of pregnancy-associated alpha 2-glycoprotein (alpha 2-PAG) in patients with hepatitis B virus (HBV) infection were compared with those of healthy male subjects used as controls by a competitive enzyme-linked immunosorbent assay (ELISA). Assay parameters were optimized, and minimal detectable concentration was 100 ng/ml. The alpha 2-PAG levels in 22/26 acute HBV patients showed a very significant statistical difference when compared with controls (x2 = 19.93, p less than 0.0005). On the other hand, 8/8 chronic persistent HBV patients showed high levels with a range between 51 to 200 ug/ml (x2 = 18.16, p less than 0.0005). There was no significant difference between asymptomatic HBsAg carriers and controls. Although alpha 2-PAG apparently exhibits immunosuppressive properties similar to other factors present in HBV infection, follow-up studies are needed to elucidate its role in the natural evolution of this disease.

Children with hemophilia A are at risk for the acquired immunodeficiency syndrome (AIDS). Clinically asymptomatic hemophiliacs demonstrate many immune abnormalities that might represent exposure to the AIDS agent through blood products or be a natural reaction to their therapy. In this study, we examined lymphocyte subset distribution in children with hemophilia A who had been exposed to HTLV-III as determined by antibody seroconversion. Seroconversion to HTLV-III was confirmed using Western blot analysis. The lymphocyte subsets studied included T4+ and T8+ cells. The distribution of lymphocyte subsets in children with hemophilia A was independent of seroconversion to HTLV-III. Children with hemophilia A treated with commercial factor VIII concentrate had normal numbers of circulating T4+ lymphocytes and significantly increased numbers of circulating T8+ lymphocytes compared with their nontransfused age-matched counterparts. An increased number of T8+ lymphocytes was not observed, however, in children treated exclusively with cryoprecipitate. These results suggest that HTLV-III alone cannot account for changes in lymphocyte subsets in hemophiliacs. Higher antigenic protein loads in factor VIII concentrate or additional factors might account for the increased absolute numbers of T8+ lymphocytes and represent a natural response to therapy.

Absolute levels of peripheral blood mononuclear cells were sequentially monitored by immunocytometry in 54 consecutive renal allograft recipients receiving azathioprine/prednisone (STD gp, N = 16) or cyclosporine with or without prednisone (CsA gp, N = 38), before and after transplantation. In the CsA group, but not in those receiving STD therapy, the mean absolute levels of all but OKT4+ cells increased significantly with the duration of therapy. In both treatment groups (STD + CsA), the mean % delta OKT4/8 ratio increased from a prerejection quiescent value of 80 +/- 6% SE to a rejection value of 120 +/- 6% (P less than .001) and fell back to 77 +/- 6% (P less than .0005) in postrejection quiescence. The sensitivity and specificity of such an elevated ratio for rejection were 84.4% and 88.6%, while positive and negative likelihood ratios were 7.40 and 0.15, respectively. In rejection, concomitant immunopathology showed a predominance of OKT8+ cells in the graft with a mean T cell subset ratio of 0.8 +/- 0.3 SE in renal biopsies compared to 2.0 +/- 0.3 for circulating cells (P less than .0125). Parallel donor-antigen-specific assay of lymphocyte-mediated cytotoxicity (LMC) became positive with graft rejection. Immunocytometry with normalization of sequential data in longitudinal analysis thus appears to be a valuable tool in immunologic laboratory monitoring of graft rejection.

The relationship of early interleukin 2 receptor (IL2R) expression to subsequent DNA synthesis by mitogen-stimulated human mononuclear cells (MC) was studied. For serial dilutions of a given mitogen, the percentage of lymphocytes expressing IL2R after 1 day of culture was plotted vs 3H-thymidine incorporation on day 3, and the IL2R value associated with a proliferative response of 50,000 counts per minute (IL2R-50K) determined. A mean IL2R-50K value of 7 characterized PHA, Con A, and OKT3 responses, while a higher mean value of 29 characterized anti-Leu 4(L4) responses. As tested in OKT3 and L4 systems, the addition of exogenous IL2 did not alter IL2R-50K values. Because both OKT3 and L4 recognize the lymphocyte CD3 antigen but react with different monocyte Fc receptors, the role of monocytes in producing elevated L4 IL2R-50K values was explored. MC from healthy L4 nonresponders (NR), induced to proliferate with L4 in the presence of responder (R) monocytes, also yielded an elevated mean IL2R-50K value of 31. In contrast, direct stimulation of R-MC, NR-MC, or NR-MC plus R monocytes by L4-coated sepharose beads produced lower mean IL2R-50K values of 12 or 13. Two-color cytofluorescence studies measuring IL2R and transferrin receptor (TR) on day 2 of culture revealed that most of the increase in IL2R+ cells in response to L4 was attributable to IL2R+TR-cells. These findings suggest that crosslinking of lymphocyte-bound soluble L4 by R monocytes leads to a uniquely elevated pattern of IL2R expression involving a disproportionate increase in the level of IL2R+TR-cells.

A low-temperature embedding technique using the polar resin Lowicryl K4M with protein A gold as a marker was utilized to localize a variety of antigens at the ultrastructural level. Carcinoembryonic antigen immunoreactivity was noted over the microvilli, secretory vacuoles, and the Golgi apparatus of normal colonic epithelium. Epithelial membrane antigen was localized to the luminal plasma membrane and cytoplasmic vesicles of glandular epithelium. The lymphoid antigens leucocyte common antigen and HLA-DR were both found on the membranes of lymphocytes and histiocytes. In addition, HLA-DR immunoreactivity was noted in the Golgi apparatus of these cells. The method described appears suitable for the localization of both surface and intracellular antigens with excellent preservation of both morphology and antigenicity.