Analysis of Major Histocompatibility Complex Gene Products in Tissues Isolated from the Developing Human Nervous System

Abstract

We have examined the expression of the major histocompatibility complex (MHC) class I and II gene products in the developing human fetal peripheral nervous system. As determined by RNA blot hybridization analysis, MHC class I RNA was readily detectable in extracts prepared from dorsal root ganglia (DRG) obtained from aborted human fetal material. However, utilizing similar methodology, it was not possible to detect MHC class II RNA. In conjunction with these studies, expression of MHC class I and II proteins in primary human fetal DRG tissue was examined by fluorescence-activated flow cytometry and protein immunoblotting. Consistent with the detection of MHC-specific RNA, the accumulation of MHC class I-specific protein was readily detectable in human fetal DRG neural cell populations with little, if any, accumulation of MHC class II-specific protein evident. These studies suggest that MHC gene products may be expressed early in the development of the human nervous system resulting in the generation of specific immunocompetent neural cell populations.

Effect of γ-Interferon on the Expression of Major Histocompatibility Complex Class I and II Gene Products in Neural Cells Isolated from the Developing Human Fetal Peripheral Nervous System

“…These studies have indicated that untreated human fetal DRG neural cell populations maintained in culture for a total of 5 days express a low level of MHC class II-specific RNA and protein. This observa tion further supports previous studies report ing MHC class II-specific protein, detectable only by FACS analysis but not by Western blot or RNA hybridization analyses [28], sug gesting a low level of MHC class II gene prod ucts in human fetal DRG neural cell popula tions which appears to be enhanced by pro longed in vitro cultivation. In addition, these findings are in agreement with studies per formed by other investigators in which low levels of MHC class II proteins were detect able on Schwann cells, satellite cells, and other resident cells of the central and periph eral nervous systems [50,51].…”

“…The assay was performed using serial dilutions of each RNA with the labeled RNA probe in excess (1X 106 cpm/ml) to allow for comparison of experimental results. As reported previously [28], untreated human fetal DRG neural cell populations contain a moderate level of MHC class I-specific RNA. However, as shown in Figure 2.…”

“…In previous studies. MHC class II-specific RNA was undetectable in human fetal DRG neural tissue [28], However, as shown in Figure 3, MHC class II-speciFic RNA was readily de tectable after human fetal DRG neural cell populations were incubated for 5 days in vitro in the absence of y-IFN treatment. In addi tion, the level of MHC class I-specific RNA was markedly increased in human fetal DRG neural cell populations treated with y-IFN.…”

“…Although previous studies have reported the detection of MHC class I but not class II RNA in human fetal DRG neural tissue [28], studies reported by Mauerhoff et al [33] dem- onstrate that the level of MHC class I and class II proteins accumulated in primary hu man fetal brain cultures could be enhanced by treatment with y-IFN. To examine the effect of y-IFN on MHC expression in the develop ing human fetal peripheral nervous system, total RNAs isolated from control cell popula tions and from 3-day-old human fetal DRG neural cell cultures after an additional 2-day incubation in the absence or presence of y-IFN were simultaneously assayed for the pres ence of MHC class I-and class 11-specific RNA sequences.…”

“…Human fetal neural cell populations were obtained from the DRG and associated spinal root and periph eral nerve after surgical removal from aborted human fetal specimens (12-16 weeks of gestational age) [28][29][30][31][32][33][34]. Primary human fetal DRG neural cells were incu bated in vitro for 3 days and subsequently treated with y-IFN (100 U/ml; Amgen Biologicals, Thousand Oaks, Calif.. USA) or exposed to an equivalent volume of phosphate-buffered saline (PBS) with continued incu bation at 37 °C.…”