Table 1.
Comparative immunological features of the human intestinal and genital tracts
| Intestinal | Genital | |
|---|---|---|
| Ig isotypes | IgA ≫> IgG | IgG > IgA In male and female secretions |
| Molecular forms of IgA | S-IgA ≫> pIgA > mIgA | S-IgA = pIgA = mIgA |
| IgA1 > < IgA2 (IgA2 dominant in the large intestine) | IgA1 > IgA2 (IgA2 dominant in the female secretions) | |
| Origin of Ig | Local ≫> systemic | Local = systemic |
| Hormonal regulation | – | +++ |
| Epithelium | Single layer of polarized enterocytes | Stratified multilayered cells in vagina and ectocervix |
| DC/Langerhans’ cells | ||
| DC-SIGN | +++ | – |
| CCR 5 | +++ | + |
| Macrophages | ||
| CD 14 | – | + |
| CD 89 (FcαR) | – | + |
| CD16 (FγR) | – | + |
| CD4 | - | ++ |
| HIV-1 infectable | – | + |
| Plasma cells | IgA ≫> IgG | IgG > IgA Endocervix |
| IgA1 > IgA2 (small intestine) | IgA2 > IgA1 | |
| IgA2 > IgA1 (large intestine) | ||
| Lymphoepithelial inductive sites | ++ | _ |
| Humoral responses to: | ||
| Local infections or immunizations | +++ | ± |
| Systemic immunization | ± | ++ |
| Intranasal immunization | ± | ++ |