Faramarz Naeim

HL-A ANTIGENS IN MYASTHENIA GRAVIS

Abstract The HL-A types of 56 Caucasian myasthenia-gravis patients were compared to those of 90 controls. Comparisons were also made between HL-A type and sex, age at onset, and thymic morphology among the patients. HL-A8 was increased in females with early age at onset, and in addition significantly correlated with the presence of thymic follicular lymphoid hyperplasia. HL-A3 was increased in males with late age at onset and was common among myasthenics with thymoma. Immune-response genes sharing a chromosomal segment with the gene determining the HL-A8 phenotype might predispose to autoimmune reactivity in myasthenics with thymic hyperplasia and early age at onset. The HL-A type of a myasthenia-gravis patient may be useful when considering the advisability of thymectomy.

The in vitro senescence of human T lymphocytes: Failure to divide is not associated with a loss of cytolytic activity or memory T cell phenotype

Normal human T lymphocytes, activated in vitro and cultured in the continuous presence of the growth factor interleukin 2 (IL2), have a limited proliferative potential. Senescent T cell cultures will not proliferate, even if restimulated by the original allogeneic stimulator cells. However, we have now observed that such restimulation induces an increase in the percentage of cells expressing the 55 kDa chain of the IL2 receptor (IL2R alpha, CD25) without any associated increase in cell number. A younger culture, which showed a comparable increase in CD25, underwent two population doublings in the same time period after restimulation. The senescent cultures, (primarily of the CD8+, cytotoxic/suppressor, phenotype), were also found to be highly potent and specific effector cells in a 51chromium release assay for cytolytic activity. Furthermore, senescent cultures maintain the surface phenotype of memory T cells. These findings demonstrate that while senescent T cells are unable to proliferate in response to restimulation or to IL2, they are able to recognize the foreign stimulator cells and to initiate an otherwise normal T cell response. Our results lend support to the hypothesis that in vitro senescence is not associated with a generalized decline in functional activity in a differentiated cell type, but with a specific event which limits cell division. Thus, the long term T lymphocyte culture system will be useful for studying the mechanism by which proliferation is blocked in these, apparently, post-mitotic cells.

Evidence for in vitro senescence of T-lymphocytes cultured from normal human peripheral blood

Long-term T-cell cultures from 15 donors of various ages were established using T-cell growth factor (TCGF). The donors were divided in equal numbers into three age groups, under 40, 40 to 80 and over 80 years of age. The cell cultures showed a growth pattern similar to the Hayflick Phenomenon observed in the cultured human fibroblasts with a limited total number of doublings. Cell cultures from younger groups grew longer with higher total number of doublings. The total number of doublings averaged 16.5, 12.2 and 6.5 for the cultured cells obtained from donors under 40, 40 to 80 and over 80 years of age respectively.

Influence of weaning-initiated dietary restriction on responses to T cell mitogens and on splenic T cell levels in a long-lived F1-hybrid mouse strain

Abstract Previous studies have shown that rodents dietarily restricted (but not malnourished) since weaning (3–4 weeks old) show prolonged maximum survivorship, inhibition of occurrence of late-life diseases and delayed onset of senescent changes in the immune system. Mitogen induced lymphocyte proliferation, known to decline with age, was examined using mice of a long-lived hybrid strain dietarily restricted at weaning. They were fed intermittently on diets enriched in protein, vitamins and salts and providing approximately 50–60% of the calories fed to control mice. In six series of experiments dietarily restricted mice showed a 2–4 fold decrease in the number of nucleated cells per spleen and a 1.3–3.3 fold increase in phytohemagglutin (PHA)-induced tritiated thymidine uptake by spleen cells. However, diet restriction did not influence splenic responses to B cell mitogens ( E. coli lipopolysaccharide and pokeweed mitogen). An increase in splenic concanavalin A (Con A) reactivity was observed in one of three experiments. The higher maximal PHA responses by restricted mice could not be attributed to kinetic differences or to mitogen concentrations. Spleen cells from restricted mice displayed higher PHA responses at both optimal and reduced cell densities. Lymph node cell yields were reduced by underfeeding but PHA responses were not altered by dietary restriction. The immediate fasting vs. feeding state of restricted mice affected both splenic PHA and Con A reactivity as restricted mice studied 48 hours from last feeding revealed lower PHA and Con A responses than were displayed by restricted mice fed 24 hours before being killed. Neither synergy nor suppression was detected in PHA-stimulated mixed cultures of control and restricted spleen cells. The increase in splenic PHA reactivity for restricted mice was associated with a 1.7 fold increase in the proportion of PHA stimulated blast cells (as judged microscopically) and a 1.7–2.0 fold increase in the proportion of splenic T cells (as shown by cytotoxicity and immunofluorescence measurements). This increase in T cell proportions in underfed spleens is not as great as the decrease in total spleen cells yielding a 1.4–2.1 fold fall in absolute T cell numbers in restricted spleens. These findings suggest that dietary restriction of a type which may be described as “undernutrition without malnutrition” raises splenic PHA response capacity at least in part by increasing the proportion of PHA-responsive T cells.

Nodular lymphoma with intracellular immunoglobulin.

A case of malignant lymphoma with vacuolated cells is presented and, as with two other recent reports, is of the nodular poorly differentiated lymphocytic type. This form of malignant lymphoma presumably is composed of neoplastic B lymphocytes, which produce intracellular immunoglobulins or fractions thereof, corresponding to various cellular vacuoles and inclusions. The vacuolated appearance of the neoplastic cells simulates mucinous or “signet ring” adenocarcinoma, which may be excluded by clinical, routine microscopic, histochemical, immunologic, and electron microscopic observations.

Bone marrow changes in patients with hairy cell leukemia treated by recombinant alpha2-interferon

Bone marrow specimens from 21 patients with hairy cell leukemia (HCL) who were entered into a program to study the efficacy of treatment with recombinant alpha 2-interferon were evaluated. Patients were treated with the interferon, 2 X 10(6) U/m2 subcutaneously three times weekly, and were scheduled to undergo bone marrow aspiration and biopsy at study entry and after three (21 patients) and six (16 patients) months of treatment. Bone marrow samples after three months of treatment showed an overall decline in cellularity, from an average of 77 +/- 20 to 57 +/- 22 per cent, with a marked decrease in the percentage of neoplastic mass (from 87 +/- 9 to 59 +/- 24 per cent). The bone marrow changes were associated with significant improvement in hematologic values, including hemoglobin levels and granulocyte and platelet counts. The bone marrow changes and improved hematologic values remained stable with continuation of interferon therapy. However complete bone marrow remission did not occur in any of the patients after three or six months of interferon therapy. The HCL cell mass in more than 60 per cent of the patients remained at or above 50 per cent of the marrow cellularity and dropped to less than 25 per cent in 14 per cent of the patients. In all of the patients increased amounts of reticulin fibers were identified in the bone marrow prior to therapy, and 89 per cent of bone marrow aspirations failed (dry tap). The amounts of reticulin fibers remained increased in most of the patients (91 per cent), with a high incidence of dry taps (73 per cent), after therapy. Interferon therapy also changed the tartrate-resistant acid phosphatase(TRAP)-positive HCL cells to TRAP-negative, suggesting inhibition of activity and/or production of TRAP in HCL cells.

The biologic significance of HL-A antigen markers in myasthenia gravis.

dermatitis herpetiformis,27-29 Hodgkin’s disease,30. 31 systemic lupus erythematosus with skin manifestation,32 juvenile diabetes,33 Grave’s disease 34 and idiopathic Addison’s disease.35 In myasthenia gravis (MG) we are aware of reports from six different laboratories indicating an increase in frequency of HL-A8 (FIGURE 1) .36-42 Our initial observations also suggested a relation between HL-A8 and thymic morphology in MG.40 Although some skepticism about the significance of HL-A in association with disease may be rai~ed,4~ studies of inbred rodents support the contention that genes associated with the major histocompatibility systems control immune responses to a variety of bacterial and other antigens.2-6 Genetic factors predisposing to autoimmune thyroiditis 4 4 t 45 and lymphocytic choriomeningitis 46 have been linked to the major histocompatibility systems. Since abnormal HL-A distribution often has been observed in diseases of possible autoimmune origin, the existence of immune response genes with linkage to the HL-A system has been We report here the results of HL-A typing in our current series of 71 Caucasian MG patients. 23

Mature T-Cell and NK-Cell Neoplasms

Mature T- and NK-cell neoplasms represent a wide spectrum of lymphoid malignancies developed from the clonal proliferation of mature T- and NK-cells. These disorders may involve bone marrow and peripheral blood (leukemia), lymphoid or extramedullary tissues (lymphoma), or both. Mature T- and NK-cell neoplasms comprise ATM ) gene mutations suggests that ATM functions as a type of tumor suppressor gene. Most T-PLL cases also show an aberrant T-cell receptor alpha (T CRA) gene rearrangement that activates TCL1 or MTCP1-B1 oncogenes.

TCL‐1, MTCP‐1 and TML‐1 gene expression profile in non‐leukemic clonal proliferations associated with ataxia‐telangiectasia

We analyzed the role of 4 genes, TCL‐1, MTCP‐1, TML‐1 and ATM, in the early pathogenesis of T cell leukemia, with particular interest in the characteristics of long‐standing non‐leukemic clonal proliferations in ataxia‐telangiectasia (A‐T) patients. Five patients were studied: 4 patients had A‐T (2 of whom had non‐leukemic clonal proliferations [ATCP]), 1 had B cell lymphoma and 1 had T‐ALL; a fifth patient with T‐PLL did not have A‐T. We measured the levels of expression for TCL‐1, MTCP‐1 and TML‐1. TCL‐1, not expressed in unstimulated mature T cells, was upregulated in the peripheral blood leukocytes (PBL) of the 2 A‐T patients with ATCP. It was also expressed in the malignant cells of the A‐T patient with B cell lymphoma and the T‐PLL cells of the patient without A‐T. In the same cells, MTCP‐1 type A was expressed equally in all 5 patients, as well as in the controls; MTCP‐1 type B transcripts were not observed. TML‐1, also not expressed in unstimulated T cells, was expressed in the PBL of one A‐T patient with ATCP and in the leukemic cells of the non‐A‐T T‐PLL patient. These expression patterns were compared to cellular immunophenotypes. The non‐leukemic clonal T cell populations had the characteristics of immature T cells. We conclude that TCL‐1 and TML‐1 play a role in cell proliferation and survival but are not pivotal genes in the progression to malignancy, even when the ATM gene is mutated. Additional genetic alterations must occur to initiate tumorigenesis.

Xenoantisera to human DR antigens: Serological and immunochemical characterization

Antibodies to DR antigens were detected using serological and immunochemical tests in sera from rabbits and goats immunized with cultured human B-lymphoid cells mixed with an anti-T-cell xenoantiserum or with partially purified DR antigens. After absorption with human red blood cells, cultured melanoma cells, and/or T-lymphoid cells, DR xenoantisera become specifically cytotoxic to B lymphocytes. Three out of nine sera tested with a panel of T-depleted peripheral lymphocytes and chronic lymphocytic leukemia cells showed correlation with DR alloantisera submitted to the Seventh International Histocompatibility Workshop. Although the correlation coefficients were lower than those obtained with DR alloantisera, the results obtained suggest that DR xenoantisera may recognize allotypic specificities.