Abstract

Previous work conducted in our laboratories, using a murine model, suggested that soluble factors secreted by tumor cells suppress lymphocyte responses. To apply this premise to human tumors, we studied the effects of UC729-6 (lymphoblastoid B-cell) and M21-HPB (malignant melanoma) conditioned media (CM) on lymphocyte proliferation assays, as well as on the growth of other cells. The CM was collected at 2-5 day intervals from cultures of UC729-6 and M21- HPB cells in serum-free media. In assays using phytohemagglutinin (PHA) and concanavalin A (ConA), mononuclear peripheral blood cells from healthy human donors showed decreased [3H]-thymidine ([3H]-Tdr) uptake in the presence of each CM when compared to controls. In assay conditions using 100% CM, mitogen stimulation was 68-85% less than that of controls and 40-50% less using 50% CM. In mixed lymphocyte cultures (MLC), addition of 50% CM to the cells also resulted in 40-50% reduction in [3H]-Tdr uptake in comparison to controls. The addition of each CM at 1% to 100% concentrations to human fibroblasts and mouse L929 cultures produced a decrease in [3H]-Tdr uptake which was directly proportional to an increase in the amount of CM present. The growth of the UC729-6 cell was inhibited by its own CM as were the L929 cells and fibroblasts, but the M21-HPB cell was not affected greatly by its own CM. Preliminary characterization of the UC729-6 CM was performed by testing 1000 M r filter concentrated CM (fCM) in mitogen-induced lymphoproliferation assays. The fCM was subjected to dialysis using membranes with Mr limits of 25,000, 15,000, and 10,000. The > 15,000 Mr limits of 25,000, 15,000, and 10,000. The > 15,000 Mr fraction demonstrated a greater degree of inhibition of lymphoproliferation than did the > 25,000 or the > 10,000 Mr fractions. Discrete treatments with acid (pH 4.5), trypsin (100 μg/ml), and heat (37°C and 56°C) were also executed. These treatments had little effect on the amount of inhibition seen. The data suggested that the supernates of UC729-6 and M21-HPB cell lines induce suppression which can be demonstrated in vitro. It is possible that in vivo occurrence of these types of tumors may circumvent anti-tumor responses via secretion of one or more soluble immunosuppressive factors.

LLU Discipline

Microbiology

Department

Microbiology

School

Graduate School

First Advisor

Daila S. Gridley

Second Advisor

James D. Kettering

Third Advisor

Raymond G. Hall

Fourth Advisor

William C. Eby

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1989

Date (Title Page)

8-1989

Language

English

Library of Congress/MESH Subject Headings

Immune Tolerance; Suppressor Factors, Immunologic; Melanoma -- immunology; Lymphoma -- immunology

Type

Thesis

Page Count

2 vi; 47

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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