IMMUNOSUPPRESSION IN EXPERIMENTAL CRYPTOCOCCOSIS - VARIATION OF SPLENIC AND THYMIC POPULATIONS AND EXPRESSION OF CLASS-II MAJOR HISTOCOMPATIBILITY COMPLEX GENE-PRODUCTS
Ce. Sotomayor et al., IMMUNOSUPPRESSION IN EXPERIMENTAL CRYPTOCOCCOSIS - VARIATION OF SPLENIC AND THYMIC POPULATIONS AND EXPRESSION OF CLASS-II MAJOR HISTOCOMPATIBILITY COMPLEX GENE-PRODUCTS, Clinical immunology and immunopathology, 77(1), 1995, pp. 19-26
Previous studies from our laboratory have shown that infection with Cr
yptococcus neoformans can trigger the production of a series of suppre
ssor cells that specifically inhibit the cell-mediated immune response
to a nonrelated antigen, the human serum albumin (HSA). In the presen
t study, we determined the variation of thymus and spleen cell populat
ions in rats infected with C. neoformans and immunized with HSA-CFA at
the time when suppressor activity was demonstrated. At 21 days postin
fection, the number and the percentage of CD4(+)CD8(+) cells were sign
ificantly increased in the thymus together with a minor imbalance in o
ther thymocytes subsets. The study of two class II molecules encoded w
ithin the major histocompatibility complex, IA and IE, showed that the
total number of class II IA-positive cells was increased in the gland
s of animals infected when compared to the glands of animals only immu
nized, while the corresponding percentages were lower than those in co
ntrol rats. On the contrary a significant increase in both the number
and the percentage of IE phenotype was observed in the thymus of infec
ted rats, compared to the animals that were only immunized and used as
a control, The IE/IA phenotype ratio within each group was increased
in rats injected with the fungus. The study of spleen populations reve
aled an increase in CD4(+) and CD8(+) cells and a decrease in the B ce
lls. The IE antigen was increased in the spleen of infected animals. T
he IA molecule expression showed no difference between the infected an
imals and the control groups. The IE/IA phenotypes ratio was mildly in
creased in the spleen of infected rats. These findings reveal that the
cryptococcal infection can render an important imbalance in the thymu
s and spleen T-cell compartment together with a significant increase i
n the expression of the IE molecule at the time when the suppressor ac
tivity was demonstrated in this model. (C) 1995 Academic Press, Inc.