Erik Langhoff

The immunosuppressive potency in vitro of physiological and synthetic steroids on lymphocyte cultures.

The immunosuppressive potency of five natural and seven synthetic steroids were tested in vitro on phytohemagglutinin (PHA) stimulated peripheral lymphocytes (PBL) and T-lymphocytes and compared to their anti-inflammatory potencies. The physiological glucocorticoid, hydrocortisone, was of intermediate immunosuppressive potency in vitro, whereas the metabolites of hydrocortisone (cortisone, dihydrocortisol, and tetrahydrocortisol) and aldosterone were without effect. The synthetic steroids, methylprednisolone and fluorohydrocortisone were both highly potent in suppressing the PHA responses of both lymphocyte subsets. Prednisolone and dexamethasone were of intermediate potency and ranked similar to hydrocortisone which is in contrast to their anti-inflammatory properties. Prednisone, the biologically inactive metabolite of prednisolone, was without immunosuppressive properties. Deoxy-deflazacort, the biologically active metabolite of deflazacort (a new oxazoline derivative of prednisolone) was comparable to prednisolone and hydrocortisone in suppressing lymphocyte proliferation but again there was a large discrepancy between the in vitro immunosuppressive effect and the anti-inflammatory potency. In conclusion, the present assay may therefore separate the immunosuppressive properties from the anti-inflammatory properties of glucocorticoids. These findings may be useful for comparison of new synthetic steroids.

Selective Expression of Human Fascin (p55) by Dendritic Leukocytes

Dendritic cells are a heterogeneous group of antigen presenting leukocytes with distinctive cell morphology and function. The highly developed capacity of dendritic cells to present antigens and the way in which cells of variable maturity differ in their ability to take up, process, and present antigens have been well characterized (1–6). Dendritic cells are derived from cells in bone marrow in vivo and are released to peripheral blood and tissues (7,8), but dendritic cells can be generated in vitro from CD34 positive precursor cells (9–13). The position of dendritic cells in the hierarchy of hematopoietic cells remains to be established but the study of human blood dendritic and progenitor dendritic cells has been restricted by the lack of selective markers for this specialized subset of antigen presenting cells. Recently, an evolutionary conserved human actin-binding protein, fascin (p55), was demonstrated to be highly expressed by circulating blood dendritic cells (14). In the course of studying the development, migration and tissues distribution of dendritic cells we took advantage of a novel monoclonal antibody against p55 to examine the differential expression of p55 in immature, circulating, and tissue dendritic cells.

In vitro immune functions in patients with minor, moderate, and severe kidney impairment

We examined the in vitro immune response of lymphocytes from 86 non‐dialyzed patients with progressive renal failure and 48 healthy control subjects by comparing the production of interleukin‐2, the mitogen‐in‐duced proliferative response and sensitivity to glucocorticoid of lymphocyte cultures. The patients were divided in three groups with minor, moderate, and severe uremia. The uremic lymphocyte responses to stimulation with concanavalin A (Con A) were significantly lower than those of control lymphocyte cultures. A similar but not significant decrease was also seen in phytohemagglutinin (PHA) and pokeweed mitogen stimulated cultures. There was no trend towards diminishing mitogen responses with decreasing renal function. The median interleukin‐2 activity in the uremic cell cultures was decreased by 50% during the culture period but the decrease was not significant. However, PHA and Con A stimulated lymphocyte cultures from all groups of patients were significantly more sensitive to the immunosuppressive effect of methylprednisolone. Thus an increased sensitivity to the immunosuppressive effect of glucocorticoid can be demonstrated in vitro at an early stage of progressive renal disease.

Human proximal tubular cells modulate allogen responses of leukocytes in vitro

The interaction between proximal tubular cells and leukocytes was examined. In co‐cultures of tubular cells and allogenic leukocytes, tubular cells expressed MHC antigens and ICAM‐1. A small number of leukocytes adhered to tubular cells and induced cytotoxic damage. Thus, 65% of the tubular cells were viable after co‐culturing with allogenic leukocytes. These cells had low alloreactive capacity, which was not due to lack of interleukin‐1 or interferon‐gamma. The presence of tubular cells modulated the immune response of leukocytes by reducing the effect of mitogen by 80%, allogens by 65% and interleukin‐2 by 40%. A soluble factor released in the co‐cultures was a likely mediator, since addition of supernatants from co‐cultures suppressed mitogen responses by 27% compared to leukocytes cultured alone. This mediator might be prostaglandin, because addition of indomethacin to co‐cultures increased the growth response of leukocytes.