Increase in serum IgE levels following injection of syngeneic keratinocyte extracts in BALB/c mice

Abstract

Increased serum IgE levels are found in atopic diseases, especially atopic dermatitis. It is generally accepted that the high serum IgE levels are increased by exposure to exogenous antigens. However, exposure to antigens in the absence of proper adjuvants does not usually increase serum IgE. Here, we studied the involvement of skin factor(s) in increasing serum IgE. The soluble fractions were obtained from two keratinocyte cell lines, PAM 212 and KCMH-1, derived from BALB/c and CBA/J mice, respectively. These were injected subcutaneously into parental mice strains at 2-week intervals. The levels of serum immunoglobulins and the release of IgE in vitro from spleen cells were measured by ELISA. The biological activity of the increased serum IgE was assessed by sensitization of RBL-2H3 mast cells with serum. Six injections of PAM 212-derived fraction (PAM extract) consistently increased the serum levels of IgE, IgG1 and IgG2b, but not those of IgM, IgG2a, IgG3 or IgA in BALB/c mice. The high serum levels of IgE were sustained for at least 10 weeks after one or two injections of PAM extract. When RBL-2H3 cells were sensitized with the serum from mice injected with PAM extract, they released histamine in response to anti-IgE. Moreover, spleen cells of these mice produced significantly higher amounts of IgE than those of uninjected mice in the presence of IL-4 and anti-CD40 antibody. On the other hand, no significant increase in immunoglobulins was observed following injection of the soluble fraction from KCMH-1 cells in CBA/J mice. These results suggest that the release of the soluble fraction of keratinocytes and its exposure to immunologically competent cells may induce an increase in serum IgE levels by a Th2-dominant mechanism.

Oral administration of pulverized Konjac glucomannan prevents the increase of plasma immunoglobulin E and immunoglobulin G levels induced by the injection of syngeneic keratinocyte extracts in BALB/c mice

“…After 14-weeks feeding of either control or PKGM diet, there was no difference in the appearance and body weight among the groups (30.2 AE 0.5 g for PBS-injected mice fed with control diet, 29.5 AE 0.4 g for PBS-injected mice fed with PKGM diet, 30.7 AE 0.3 g for PAM extractinjected mice fed with control diet, 30.0 AE 0.3 g for PAMextract-injected mice fed with KGM diet). In accordance with our previous report [17], continual injection of PAM extract induced the increase of plasma IgG and IgE levels during the period of the experiment in mice fed with control diet. The levels of plasma IgG and IgE in mice fed with PKGM were significantly lower than those in mice fed with control diet: IgG at 5 and 11 weeks ( Fig.…”

“…In general, Th2 cells drive B cells to differentiate and produce Igs by secretion of cytokines such as IL-4 and IL-13. In addition, our previous study has shown that the injections of PAM extract consistently increased the levels of serum IgE, IgG1 and IgG2b [17], suggesting the enhancement of Th2 cellular responses. Thus, the results of this study suggested that PKGM suppresses Th2 cellular responses.…”

“…According to this hypothesis, destruction or stress of the skin may be more important than exposure to exogenous antigens in atopic dermatitis. Indeed, we have demonstrated that continual injection of syngeneic keratinocyte (PAM-212 cells) extracts (PAM extract) without adjuvant induced the increase of serum IgE, IgG1 and IgG2b levels without developing skin lesions in BALB/c mouse [17]. This result suggested that PAM extract might initiate the increase of serum Ig levels by a Th2-dominant mechanism.…”

“…PKGM was a gift from Shimizu Chemical (Mihara, Japan), and its mean particle sizes were estimated to be about 77 mm. Keratinocyte cellular extract was prepared as described previously [17]. Briefly, PAM 212 cells, a murine keratinocyte cell line derived from BALB/c mouse [19], were cultured and harvested at subconfluence.…”

The extract of syngeneic keratinocytes enhances IgE production from BALB/c mouse splenic lymphocytes in vitro

“…Based on these findings, we hypothesized that skin damage, especially destruction of the epidermis, raises serum IgE. We previously revealed that serum IgE level of BALB/c mouse increased when injected with syngeneic keratinocyte extract, and that this phenomenon was not clearly observed in CBA/j mouse [19], suggesting the close association of genetic background with the effect of keratinocyte extract. It is well known that B-cells produce IgE protein via immunoglobulin class-switching triggered by epsilon germ-line transcription under the influence of both interleukin (IL)-4 and CD40L-CD40 interaction [9].…”