# SECRETORY IGA SYSTEM--MOLECULAR-CELLULAR INTERACTIONS

> **NIH NIH R01** · UNIVERSITY OF ALABAMA AT BIRMINGHAM · 1990 · $189,904

## Abstract

In healthy adults the total daily production of IgA exceeds that of other
immunoglobulin classes.  Molecules of representative secretory and serum
IgA differ both in their predominant molecular forms (proportion of IgA1
and IgA2 subclasses as well as polymers and monomers) and sites of
production.  The objective of the proposed investigation is to determine
molecular-cellular mechanisms that regulate synthesis and catabolism of
IgA.  A team of investigators experienced in hybridoma technology and
molecular cloning will study the biochemical and genetic events that occur
at the earliest stages of human B cell differentiation with the particular
emphasis on the importance of J chain expression.  This low molecular
weight glycoprotein, previously thought to be involved in polymerization
and transport of immunoglobulins into external secretions, is likely to
have a more fundamental role in B cell ontogeny.  It may be expressed
before or independently of immunoglobulin chains.  Therefore, we shall
determine the tissue distribution and properties of J chain-positive cells
in unstimulated cells and transformed cell lines of human fetal
lymphocytes.  The quantity, molecular form, and subcellular localization of
J chain will be determined by radioimmunoassay and immunohistochemical
procedures.  The participation of J chain in the process of intracellular
assembly will be explored in vitro and in vivo taking advantage of already
available cell lines that express only J chain.  These cells will be fused
with monomeric IgA-secreting cell lines.  Native J chain (obtained from
cell lysates or as a cloned products) will be examined for its ability to
polymerize monomeric immunoglobulin in vitro.  The synthesis of IgA by
plasma cells and their precursors is regulated by T cells and/or their
products.  Thus, we shall study the regulatory role of T cells isolated
from human colostrum, the quintessential product of the secretory IgA
system.  T cells from other sites will be also evaluated for their
potential to regulate IgA synthesis in vitro.  In contrast to our knowledge
of the synthetic sites and large quantitites of IgA produced, its
catabolism remains undefined.  Accordingly, we shall examine the fate and
tissue distribution of catabolized IgA.

## Key facts

- **NIH application ID:** 3124835
- **Project number:** 5R01AI010854-19
- **Recipient organization:** UNIVERSITY OF ALABAMA AT BIRMINGHAM
- **SAM.gov UEI:** YND4PLMC9AN7
- **Principal Investigator:** JIRI F MESTECKY
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1990
- **Award amount:** $189,904
- **Award type:** 5
- **Project period:** 1978-08-01 → 1992-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3124835

## Citation

> US National Institutes of Health, RePORTER application 3124835, SECRETORY IGA SYSTEM--MOLECULAR-CELLULAR INTERACTIONS (5R01AI010854-19). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3124835. Licensed CC0.

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