Adhesion of peripheral blood lymphocytes of children with arthritis to human umbilical vein endothelial cells.

To determine whether adhesion of peripheral blood lymphocytes (PBL) of patients with juvenile rheumatoid arthritis (JRA) may be enhanced, adhesion of PBL of children with JRA, children with seronegative spondyloarthropathies (SSA), age-appropriate and adult controls, to human umbilical vein endothelial cells (HUVEC) was assessed in vitro. B and CD4 T lymphocytes in initial, adherent, and non-adherent cell fraction were identified by flow cytometry. B lymphocytes of all the younger subjects combined had a higher adherence to activated HUVEC compared with B lymphocytes of the adult donors. Except for greater adherence of HLA-DR+ CD4 T cells, lymphocytes of children with JRA showed no enhanced adhesion to either unactivated or activated HUVEC. The percentage of B cells adherent to activated HUVEC in each of the subject groups was 1.5-3.6-fold higher than adherent CD4 T lymphocytes. Surface analyses indicated higher percentages of CD49d (alpha 4)+ and CD29 (beta 1)+ CD4 T lymphocytes in adherent cells, but less of a differential in CD49 (alpha 4)+ and no difference in CD29 (beta 1)+ B lymphocytes. There were fewer Leu-8 (L-selectin)+ B and Leu-8+ CD4 T cells among adherent cells. The data suggest a greater adhesive capacity of B lymphocytes compared with CD4 T lymphocytes which is unrelated to disease, and the possibility that B lymphocytes may utilize adhesion molecules distinct from those of CD4 T lymphocytes. Only a small subset of T cells of patients with JRA may have an enhanced capacity for adhesion to endothelium.     

Inhibition of proliferative responses of mouse spleen lymphocytes by bovine milk κ‐casein digests

The inhibitory effects of bovine milk κ‐casein and its enzymatic digests on the proliferative responses of mouse spleen lymphocytes induced or not induced by mitogens were studied with a colorimetric assay using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT). κ‐Casein and its glyco‐macropeptide (residues 106–169) inhibited the lipopolysaccharide (LPS)‐induced proliferative response, but the inhibitory effect was lost significantly after neuraminidase and chymotrypsin digestions. In contrast, trypsin and pronase digestions of K‐casein increased inhibitory effects. The pronase digest inhibited the proliferative responses not only induced by LPS but also in the absence of mitogen or when induced by concanavalin A and phytohemagglutinin. The pronase digest seemed to possess weak cytotoxity for lymphocytes. The inhibitory peptide was a glycopeptide(s) having specific size, and the inhibitory effects were reduced significantly by neuraminidase and chymotrypsin digestions. Moreover, similar inhibitory effects on proliferation of lymphocytes were observed in pronase‐digested bovine milk αs₁‐casein and β‐casein. These findings suggest that some peptides produced from milk caseins by the action of gastrointestinal proteinases might contribute to down‐regulate the immune response of neonates.     

The Immune Reactivity Role of HCV-Induced Liver Infiltrating Lymphocytes in Hepatocellular Damage

Liver infiltrating lymphocytes (LIL) were isolated from HCV-positive (+) and HCV-negative (–) end-stage livers. Phenotypic analysis and functional studies using proliferative and lymphocytotoxic assays were performed with the isolated LIL. Two CD3+ lymphocyte populations were found in LIL using FITC anti-CD3 monoclonal antibodies (mAb). One was a bright fluorescence intensity population (as in PBL), and the other dim. We calculated the number of FITC-anti-CD3 mAbs bound per lymphocyte on PBL and LIL and found 80,040 ± 4628 and 39,615 ± 3932, respectively. Therefore, HCV+ and HCV– patient PBL contained approximately twice the number of CD3 molecules per cell than patient CD3+ LIL. LIL also contained approximately a threefold higher concentration of TCR+, CD4–CD8–, and CD56,16 (NK) cells than the patient PBL. Thus, a major subset of LIL is phenotypically similar to mouse NK1.1+ intermediate T cells. LIL freshly isolated from HCV+ livers exhibited weak CTL activity against EBV- or Con A-transformed lymphoblast targets infected with vaccinia–HCV recombinant virus (rHCV) or primary hepatocyte cultured cells. However, after in vitro coculture of LIL with rHCV, these cells developed a strong cytotoxicity for the above targets. In contrast, LIL from HCV– livers were not cytotoxic against the same targets. Histochemical studies (in situ) demonstrated that these hepatocytes express CD95, and stains demonstrated apoptosis. The HCV+ hepatocytes also express class I MHC molecules and ICAM-1. The addition of mAb specific for these adhesion molecules inhibited CML activity. Short-term cultured hepatocytes (targets) from HCV+ and HCV– patients produced low levels of cytokines IL-1, IL-2, IL-6, TNF, and IFN- but a high level of IL-8. It is speculated that LIL expressing reduced numbers of CD3 molecules may even function as immune regulators as proposed for intermediate T cells in mice.     

Use of liposomes to studycAMP transport by lymphocyte membranes

Institute of Immunology, Ministry of Health of the USSR. (Presented by Academician of the Academy of Medical Sciences of the USSR A. D. Ado.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 109, No. 3, pp. 246–248, March, 1990.     

Appearance of extrachromosomal circular DNAs during in vivo and in vitro ageing of mammalian cells

Appearance of extrachromosomal circular DNAs with in vivo and in vitro cellular ageing was examined by using a new technique of mica-press-adsorption for electron microscopy. The size distribution and the copy number of circular DNA complexes varied, depending on the cellular age. Extrachromosomal circular DNA complexes of variable length of more than 0.5 microns or 1.5 kilobase (kb) appeared during in vivo ageing of rat lymphocytes and in vitro ageing of cultured human lung fibroblasts. A restricted size class of circular forms of less than 0.5 microns in contour length was amplified in human skin fibroblasts from aged normal or Werner's syndrome subjects. These circular DNA molecules are suggested to be products of DNA rearrangements or gene amplification occurring in the chromosome.     

T suppressor lymphocytes reverse ongoing acute allograft rejection

(LEW X BN)F1 cardiac allografts are rejected within 8 days in untreated LEW recipients. At the critical time point of 5 days after transplantation, the obviously rejecting grafts are enlarged and maximally infiltrated by host cells as shown by 111In-labeled lymphocyte tracer studies. However, when such hearts were retransplanted back to naive (LEW X BN)F1 secondary hosts, they survive indefinitely, showing that even late rejection is reversible in the absence of sustained host immunological drive. Attempts were then made to abrogate this advanced immune responsiveness using Cyclosporine (CsA). CsA therapy (15 mg/kg/day for 7 days) starting from day 5 produced indefinite graft survival, similar as if initiated at the time of operation. Addition of exogenous IL-2, which drives the proliferation of Tc, could not reverse this effect. Serial changes in phenotype of lymphocyte subpopulations infiltrating both acutely rejecting and indefinitely functioning cardiac allografts in unmodified and CsA treated hosts, respectively, were then studied. Ratio of Th:Tc/s cells in acutely rejecting grafts was 1.6 by day 3; it inverted abruptly to 0.7 by day 5-6, suggesting predominance of Tc/s during the later stages of allograft rejection. Similarly, treatment with CsA produced a transient depression of Th, with recovery of original Th:Tc/s ratio during the next 2-3 weeks. Adoptive transfer experiments were then performed to investigate the functional significance of these findings.(ABSTRACT TRUNCATED AT 250 WORDS)     

IL-12 inhibits in vitro immunoglobulin production by human lupus peripheral blood mononuclear cells (PBMC)

Systemic lupus erythematosus (SLE) is a prototypical autoimmune disease characterized by polyclonal B cell activation and by the production of anti-double-stranded (ds) DNA antibodies. Given the inhibitory effects of IL-12 on humoral immune responses, we investigated whether IL-12 displayed such an activity on in vitro immunoglobulin production by SLE PBMC. Spontaneous IgG, IgG1, IgG2, IgG3 and IgM antibody production was dramatically reduced by addition of IL-12. These results were confirmed by Elispot assays detecting IgG- and anti-dsDNA-secreting cells. While IL-6 and TNF titres measured in PBMC supernatants were not modified by addition of IL-12, interferon-gamma (IFN-γ) titres were up-regulated and IL-10 production down-regulated. Since addition of IFN-γ did not down-regulate immunoglobulin production and since the inhibitory activity of IL-12 on immunoglobulin synthesis was not suppressed by anti-IFN-γ antibody, we concluded that the effect of IL-12 on immunoglobulin production was not mediated through IFN-γ. Our data also argue against the possibility that down-regulation of endogenous IL-10 production was responsible for the effect of IL-12. Thus, inhibition of IL-10 production by IFN-γ was not accompanied by inhibition of immunoglobulin production, and conversely, restoration of IL-10 production by anti-IFN-γ antibody did not suppress the inhibitory activity exerted by IL-12 on immunoglobulin production. Taken together, our data indicate that reduction of excessive immunoglobulin and anti-dsDNA antibody production by lupus PBMC can be achieved in vitro by IL-12, independently of IFN-γ and IL-10 modulation.     

Electrophoretic fractionation of murine lymphoid cells. I. Enrichment of peripheral T lymphocyte subsets with distinct surface phenotypes

The purpose of this work was to evaluate the efficiency of free-flow electrophoresis as a method for separating mouse lymphocyte subsets. The surface phenotype of the cells contained in the various fractions collected after electrophoresis of CBA/J lymph node cells was investigated by means of single- and 2-color flow cytofluorometry (FCF) analysis. In agreement with previous works, B cells (sIg+, Thy-1-) were found to segregate in the low mobility (LM) fractions and T cells (sIg-, Thy-1+) in the high-mobility (HM) fractions. While the mean fluorescence intensity of sIg staining did not significantly vary as a function of electrophoretic mobility (EPM) that of Thy-1 staining tended to decrease with increasing EPM. The distribution of Lyt-1+ cells was roughly parallel to that of Thy-1+ cells. However, 2-color FCF analysis suggested the existence, in addition to a major Thy-1+ Lyt-1+ subpopulation, of a minor subset of Thy-1- Lyt-1+ cells. Lyt-2+ cells made up a peak in the cathodic HM region where they were enriched by up to 3-fold, and a trail in the more anodic HM fractions. Two-color FCF analysis showed that all Lyt-2+ cells recovered in these various electrophoretic fractions expressed the Lyt-1 antigen. Taken together, these data demonstrate that free-flow electrophoresis provides a powerful tool for the delineation and substantial enrichment of phenotypically distinct mouse peripheral T cell subsets.     

The enhancement of antibody response by IgM antibodies is dependent on antigen-specific T helper cells

The enhancement of antibody responses by IgM antibodies administered with low doses of antigen has been studied in a T-dependent (SRBC) and an T-independent (alpha 1,6 dextran) system. It has been found that IgM anti-SRBC antibodies do not enhance a SRBC response in nude mice. The T-cell dependency was also directly demonstrated by showing the effect of IgM on T-cell priming in transfer experiments. The simultaneous injection of antigen and IgM antibody also induced a polyclonal increase of IgM, PFC, which was not due to a non-specific "adjuvant" effect of IgM, as we could not detect a similar effect on an ongoing response to HRBC in mice simultaneously given SRBC and IgM anti-SRBC antibodies. The specificity of the helper cell for either the antibody or the antigen was investigated in a response to alpha 1, 6 dextran, in which we could demonstrate antibody-specific helper T cells, but no antigen-specific help. We have found that IgM anti-dextran antibodies do not enhance and rather suppress the response of normal, high-responder mice, to dextran, suggesting that the T cells mediating the "19S enhancement" are antigen-specific. The magnitude of the enhancement response, as compared to the responses induced by either antigen or antibody alone, implies a synergistic mechanism, possibly involving antigen-specific and antibody(idiotype)-specific T helper cells.