Activation of cytokine genes during primary and anamnestic immune response to inactivated C. albicans
Authors: ROSATI E. , SCARINGI L. , CORNACCHIONE P. , FETTUCCIARI K. , SABATINI R. , MEZZASOMA L. , BENEDETTI C. , CIANETTI S. , ROSSI R. , MARCONI P. 
Published: November 2003

Recent evidence suggests that after repeated stimulations with inactivated C. albicans (CA) cells, CD2F1 mice respond with a cytokine pattern typical of T‐helper 1 (Th1) subset development. The purpose of this study was to analyse the sequence of immunological events which, soon after priming mice with CA, lead to the development of primary and anamnestic response. A comprehensive kinetics analysis of cytokine mRNA expression was performed by Northern blot assay, in peritoneal exudate cells (PEC), at different phases of immune response to CA: after priming (one i.p. injection of 2×107 CA cells/mouse), during development of the primary immune response (five progressive CA i.p. injections over a 2‐week period) and in the anamnestic response (CA booster 30days after the primary response). In vitro assays were performed 2 and 24hr after every CA stimulation. The response to CA priming was characterized by an early and high expression of interleukin‐2 (IL‐2) and IL‐1β mRNAs. At 24hr, IL‐2 mRNA was still at a high level, while IL‐1β had greatly decreased. A weak expression of IL‐10 was only induced at 2hr, whereas IL‐12 p40 subunit, interferon‐γ (IFN‐γ), IL‐4 and IL‐5 mRNAs were undetectable. In this phase no in vitro proliferative response of PEC to CA was observed, whereas a significant natural killer (NK) activity was induced. From the second CA injection, the IFN‐γ mRNA was already induced at 2hr. Its expression level increased progressively with the number of CA injections persisting up to 24hr after the fifth stimulation. A progressive increase of IL‐2 mRNA expression was also induced whereas IL‐1β and IL‐10 mRNAs were always transiently expressed at 2hr at levels similar to those observed after the priming. IL‐12 p40 subunit, IL‐4 and IL‐5 mRNAs were never detectable. The expression of this selected cytokine pattern typical of Th1 response was correlated with the development of CA‐specific T lymphocytes as confirmed by the in vitro proliferative response of CA‐5d‐induced PEC to CA. NK activity also increased progressively with the number of CA injections and after the fifth stimulation lymphokine‐activated killer (LAK) activity was also induced. The anamnestic response to CA was characterized by a very quick induction of high levels of IL‐2, IFN‐γ and IL‐1β mRNAs. IL‐2 and IFN‐γ mRNAs remained high up to 24hr while IL‐1β mRNA decreased strongly. A weak, transient expression of IL‐10 mRNA was induced at 2hr whereas the IL‐12 p40 subunit, IL‐4 and IL‐5 mRNAs were not detectable. The presence of CA‐specific memory lymphocytes was confirmed by the in vitro specific proliferative response of PEC to CA. CA booster caused also a very rapid and high level of NK/LAK activation. In conclusion, these results indicate that CA is able to progressively trigger differentiation of the Th1 subset which develops in the absence of IL‐12, and that Th memory cells retain the same selected Th1 cytokine profile developed in the primary immune response.