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Biomedical subjects

A N Akbar

Publications and source records attributed to A N Akbar.

79 records · Page 5Linked to original sources
PubMed1985

Disproportionate lymphoid cell subsets in thalassaemia major: the relative contributions of transfusion and splenectomy.

The relative proportions of T-cell (OKT3-positive, OKT4-positive and OKT8-positive) and B-cell (SIg-positive) populations in peripheral blood obtained from 29 chronically transfused patients with beta-thalassaemia major were compared with those of 17 healthy controls. Changes attributable to blood transfusion and/or splenectomy are described. The percentage of OKT8-positive (T-suppressor) cells found in the thalassaemic patients increased linearly (P less than 0.001) with the number of units transfused, irrespective of splenectomy. The percentage of OKT4-positive (T-helper) cells varied inversely with increasing transfusion in nonsplenectomized patients while in those who were splenectomized no significant correlation was apparent. Thus, in both groups of patients the T4/T8 ratio declined in a transfusion-related manner. The splenectomized patients experienced a marked and persistent lymphocytosis due to an increase in the number of both T- and B-cells. When the results were expressed as percentages, the greatest increase occurred in the number of B-cells, this increase being unrelated to the number of transfusions received. None of the serum parameters usually associated with iron overload or abnormal liver function correlated with the observed increases in T-suppressor and SIg-positive cells. These findings corroborate reports that transfusion of blood products may lead to decreased T4/T8 ratios. However, none of the patients studied manifested clinical signs of acquired immune deficiency syndrome (AIDS). Accordingly, studies which define transfusion related AIDS on the basis of analyses with monoclonal antibodies must be viewed with caution.

Adolescent↗
PubMed1985

Immunological abnormalities in thalassaemia major. I. A transfusion-related increase in circulating cytoplasmic immunoglobulin-positive cells.

Multiply transfused patients with beta-thalassaemia major have elevated serum immunoglobulin levels and a transfusion-related increase in (T8+) T-suppressor cells. We report here that these patients also have a significantly increased (P less than 0.001) proportion of B-cells that contain cytoplasmic immunoglobulin when visualized immediately upon isolation. On the other hand, the same cell populations do not exhibit an increase in the proportion of immunoglobulin-secreting cells as measured by a reverse haemolytic plaque assay. These results, together with those of ongoing studies, suggest that the cells containing the cytoplasmic immunoglobulin are likely to be terminally differentiated B-cells which persist in the circulation. While the reason for this phenomenon is not yet known, we have found that the increase in these cells is transfusion-related.

B-Lymphocytes↗
PubMed1984

Spontaneous and Concanavalin A-induced suppressor activity in control and Hodgkin's disease patients.

Indirect evidence suggests that abnormal regulation of B cells exists in Hodgkin's disease (HD) due, perhaps, to the sequestration of regulatory T-lymphocyte subpopulations in the spleen in this condition. Other work implicates the B-cell itself in this abnormality. In this study we have attempted to measure regulatory T-cell function by quantitating spontaneous and Concanavalin A(Con A)-induced suppressor activity in T-enriched spleen cells from control and HD spleens for pokeweed mitogen(PWM)-induced immunoglobulin (Ig) production. Using this polyclonal system, HD patients' spleen T-lymphocytes could not be shown to differ markedly from the control series. Cells capable of spontaneous and mitogen-induced modulation of Ig synthesis were present in both populations and showed a reciprocal relationship implying the activation of the same cell type. In this respect HD and control spleen resembled peripheral blood. A limited parallel investigation of PWM-regulatory activity in cells from spleen and peripheral blood from individual patients was also undertaken. Individual patients showed wide variation in suppression between the two compartments and, therefore, measurements of functional capacity in blood alone may not provide a true estimate of total regulatory capacity in lymphoma patients.

B-Lymphocytes↗
PubMed1984

Suppression of the mixed lymphocyte reaction by alloantigen-primed and -stimulated human spleen lymphocytes.

This communication examines the ability of T cell-enriched preparations from human spleen to suppress lymphocyte proliferation following activation in the mixed lymphocyte reaction (MLR). To enable the generation of a subsequent responding MLR between identical partners to those employed in the initial (stimulating) MLR, spleen T cells were frozen at the time of the first culture. Spleen T cells, stimulated in this way, showed a marked ability to suppress human MLR responses, but HLA-D identity was required for the full expression of suppressor activity. The characteristics of the spleen MLR-induced suppressor T cell resemble closely those described for MLR-generated suppressor T cells in human peripheral blood.

Adult↗
PubMed1983

Immunological reason for chronic ill health after infectious mononucleosis.

In a group of patients who suffered from chronic ill health after an attack of acute infectious mononucleosis a disorder of T cell regulation was found. By means of cytochemical reactions the staining pattern associated with T suppressor cells was found in a greater percentage and that associated with T helper cells in a smaller percentage than in normal subjects. In a few patients this finding was confirmed in a functional suppressor assay. The patients were unwell for at least a year but most later made a complete recovery, which was associated with return to normal of the lymphocyte subsets.

Adolescent↗
PubMedDate not supplied

The role of the immune system in conjunctival wound healing after glaucoma surgery.

The immune system has a fundamental role in the development and regulation of ocular healing, which plays an important role in the pathogenesis of most blinding diseases. This review discusses the mechanisms of normal wound healing, describing the animal and fetal wound healing models used to provide further insight into normal wound repair. In particular, conjunctival wound repair after glaucoma filtration surgery will be used to illustrate the contributions that the different components of the immune system make to the healing process. The potential role of macrophages, the possible regulatory effect of lymphocytes, and the important role of growth factors and cytokines in the wound healing reaction are discussed. The significance of the immune system in the pathogenesis of aggressive conjunctival scarring is addressed, particularly assessing the predisposing factors, including drugs, age, and ethnicity. The rationale behind the pharmacological agents currently used to modulate the wound healing response and the effects these drugs have on the function of the immune system are described. Finally, potential new therapeutic approaches to regulating the wound healing response are reported.

Animals↗