HgCl2 and IL4 differentially modify expression of major histocompatibility complex class II molecules RT1.B and RT1.D in B lymphocytes from brown Norway and Lewis rats

Magnetic resonance imaging of major histocompatibility class II expression in the renal medulla using immunotargeted superparamagnetic iron oxide nanoparticles

We demonstrate the development and successful application of immunotargeted superparamagnetic iron oxide nanoparticles (ITSIONs), with in vivo magnetic resonance diagnostic and potential drug delivery capability for kidney disease. Further, the versatility of the conjugation chemistry presents an attractive route to the preparation of a range of biomolecule-nanoparticle conjugates. The ITSION contrast agent is a stable, biocompatible, targeted nanoparticle complex that combines a monodisperse iron oxide nanoparticle core with a functionalized phospholipid coating conjugated to antibodies that is capable of targeting normal cells expressing specific target antigens. The plasma half-life and R1 and R2 relaxivities suggest sufficient time for targeted binding while clearing from the system quick enough for detection of specific contrast enhancement. RT1 anti-MHC Class II antibodies were used to target the renal medulla of the rat, a section of the kidney in which MHC Class II, associated with inflammation, is specifically expressed. For in vivo resonance imaging, we compare phospholipid coated nanoparticles, nonspecific ITSIONs, and RT1 ITSIONs. Enhanced binding of the RT1 ITSIONS indicates specificity for the renal medulla and thus potential for disease detection or drug delivery.

Differential regulation of expression of the MHC class II molecules RT1.B and RT1.D on rat B lymphocytes: effects of interleukin-4, interleukin-13 and interferon-gamma

Susceptibility to induction of both T helper 1- (Th1) and Th2-mediated autoimmunity is multifactorial and involves genetic linkage to the major histocompatibility complex (MHC) class II haplotype. Brown Norway (BN) rats exposed to mercuric chloride develop a Th2-dependent systemic autoimmunity, whereas Lewis rats, which are highly susceptible to Th1-mediated autoimmunity, develop immune suppression after mercuric chloride exposure. Exposure to mercuric chloride is known to enhance B-lymphocyte expression of the MHC class II molecule RT1.B, predominantly in BN rats. We demonstrate that, in contrast, expression of RT1.D was unmodified on these B cells, whereas both RT1.B and RT1.D were up-regulated on epithelial cells. Regulation of B-cell MHC class II isotype expression was further studied in vitro, using BN rat lymph node (LN) cells. Interleukin-4 (IL-4) strongly enhanced B-cell expression of RT1.B (2.8-fold), whereas RT1.D expression was only slightly, although significantly, modified (1.2-fold). B cells from Lewis rats showed a similar IL-4-induced enhancement of RT1.B expression (2.5-fold), whereas, in contrast, RT1.D expression was unmodified. Exposure of LN cells from BN rats to interferon-gamma induced a moderate increase of B-cell MHC class II expression, predominantly of RT1.B. Strong and rapid enhancement of B-cell RT1.D expression was observed after stimulation by phorbol 12-myristate 13-acetate and ionomycin. Rat IL-13 did not modify B-cell MHC class II expression; however, it induced typical morphological changes in peritoneal macrophages. These experiments demonstrate isotype-specific and strain-dependent regulation of MHC class II expression on rat B lymphocytes, which may be of pathophysiological relevance for the strain-dependent susceptibility for Th1- or Th2-mediated autoimmunity.