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Delayed type hypersensitivity plays an important role in immune
system. When an antigen encounteres an antigen-specific T cell
could induce the local inflammation which help the host defence
against foreign pathogens. Some substances in the dialy- zable
leukocyte extract from a sensitized donor could transfer an
anitgen-specific delayed type hypersensitivity to naive recipi-
ent. This substance(s) was named transfer factor. In 1989, Lei
et al. reported another novel type of hypersensitivity. They
found that certain components in the culture supernatant of
sensitized splenocyte could transfer the early type
hypersensitivity in an anitgen-specific manner. Culture
supernatant containing transfer factor from HBsAg immunized
mice were purified by gel filtration and devided into several
fractions based on its molecular weight. These fractions were
tested for their effect on T cell prolifer- ation. We found
that fraction 1 and 2 inhibite the T cell proliferation in an
HBsAg-specific manner while faction 3 inhibit nonspecifically.
The data showed that TF1 was not cyto- toxic to cells whenever
in high or low dose, and low dose of TF1 inhibited antigen-
specific cell proliferation. It's possible that TF1 is the
component of transfer factor with antigen-specificity. The cell
viability was decreased after treatment with TF2 or TF3. TF3
was very cytotoxic even at low dose which might explain why TF3
inhibited T-cell proliferation nonspecifically. Exogenous
addition of IL-2 reversed the transfer factor-mediated inhibi-
tion. When IL-2 receptor (IL-2R) of the cells was analyzed, it
was found that the cytoplasmic IL-2R, but not surface IL-2R,
was decreased after transfer factor and antigen treatment. This
might be one of the mechanism that transfer factor inhibit the
T-cell proliferation in vitro.
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