## LSU Historical Dissertations and Theses

1996

Dissertation

#### Degree Name

Doctor of Philosophy (PhD)

#### Department

Veterinary Medical Sciences - Pathobiological Sciences

Thomas R. Klei

#### Abstract

Cytokines play an important role in regulation of T cell responses. Two T helper cell subsets have been identified in some species and are defined by their cytokine secretion profiles. Th1 cells produce IL-2 and IFN-$\gamma,$ whereas Th2 cells express IL-4, IL-5, and IL-10. Precursor T cells that express a mixture of these cytokines are considered Th0 cells. It is hypothesized that primary infections of Brugia pahangi in gerbils induce an initial Th0 or Th1 like response which with time becomes a Th2 like response. To test this dynamic parasitism induced shift in cytokine profile, it is necessary to measure the expression level of cytokines that differentiate the Th1 and Th2 responses. For this purpose, the full length cDNAs of gerbil IL-2, IL-4, IL-5, IL-10, IFN-$\gamma$ and HPRT were first isolated using cross-species PCR, inverse PCR or RACE and conventional PCR techniques. Subsequently, a competitive RT-PCR ELISA for quantitation of gerbil cytokine mRNAs was developed. Using this assay, the profile of gerbil cytokine response was measured during a primary infection of Brugia pahangi. Increased levels of IL-2, and IL-5 were seen during the initial stages of the infection at 14 to 28 days post-infection (DPI). An increase in IL-4 was first detected 28 DPI in renal lymph nodes and continued to increase during the infection. Increased levels of IL-10 were first seen in the spleen 56 DPI and in all tissues at 150 DPI. These initial results are in agreement with the hypothesis proposed. In addition to the development of this cytokine measuring method, gerbil IL-2 cDNA was expressed in both eucaryotic and procaryotic expression systems. Pure and functional recombinant gerbil IL-2 (gIL-2) was obtained using the pMAL procaryotic system. Further, neutralizing anti-gIL-2 antibodies were raised in rabbits. The immunological reagents produced plus the cytokine quantitation assay established make it possible to initially measure immunologic responses in the gerbil. These types of measurements will advance the understanding of immunologic and pathologic responses of filariasis, using the gerbil-Brugia model. These methodologies also will expand the usefulness of this unique laboratory animal, in studies of other diseases.

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