|Year : 1997 | Volume
| Issue : 2 | Page : 91-94
An immunological study of vitiligo
Source of Support: None, Conflict of Interest: None
Estimation of peripheral T lymphocytes T3, T4, T8 and NK cells was carried out in 30 cases of different clinical types of vitiligo by direct immunofluorescence technique. The cases were divided into two broad groups (1) Localised; and (2) Generalised. These cases were again divided into 3 groups as per duration of disease. Thirty healthy subjects served as control. Decrease in T3 and T4 and increase in T8 with decrease of T4/T8 ratio was seen in both localised and generalised variety. But the T4/T8 ratio was decreased to a greater extent in generalised variety. The NK cells showed significant increase in the generalised variety. As per disease T4/T8 ratio was reduced maximally in patients with disease duration less than one year. Of the generalised category NK cells were increased more in patients having disease duration more than 1 year.
Keywords: Vitiligo, T lymphocyte subsets, Natural killer cells
|How to cite this article:|
Sinha A. An immunological study of vitiligo. Indian J Dermatol Venereol Leprol 1997;63:91-4
| Introduction|| |
Vitiligo is a common, acquired, sometimes heritable melanocytopenic disorder of the skin. It is characterised by progressive, well circumscribed, cutaneous white macules, ocular abnormalities and a significant incidence of associated disorders, particularly thyroid disease, diabetes mellitus and premature leukotrichia.
Regarding causation there are 3 main theories. They are autoimmune, neurotoxic and autocytotoxic. A statistically significant decrease in T helper cell and increase in T suppressor cells and Natural Killer cells (NK) have been shown.
After seeing the recent stress laid on immunologic mechanisms, the recent study was conducted to examine the levels of T3, T4, T8 and NK cells in various clinical types of vitiligo with different disease durations.
| Materials and Methods|| |
The study comprised of 40 consecutive cases for clinical studies. Out of these, 30 cases were selected according to clinical types for immunologic study and 30 healthy controls were considered.
On the basis of clinical observation, vitiligo cases were divided into:
- (A) Localised -(i) focal; (ii) segmental.
- (B) Generalised -(i) vulgaris; (ii) acrofacial; (iii) universal.
The cases were again subdivided as per disease duration:
- (A) less than 1 year;
- (B) more than 1 year but less than 3 years;
- (C) more than 3 years.
All patients and controls were screened for HIV by ELISA and confirmed by Western Blot analysis.
For counting lymphocyte subsets and NK cells, we used the direct immunofluorescence technique using commercially available monoclonal antibody (MAB) tagged with fluorescein isothiocyanate (FITC) at the Department of Immunology, National Institute of Cholera and Enteric Diseases, Calcutta.
MAB OKT3, OKT4 and OKT8 (Orthodiagnostic, New Jersy, USA) were used for identification of T lymphocytes and its subsets. MAB antihuman Leu 7 (Becton Dickinson, Denmark) was used for NK cell identification.
| Results|| |
Out of the 30 cases studied, 20 had generalised and 10 had localised vitiligo. The results obtained in our study are given in [Table - 1] to [Table - 4].
| Discussion|| |
As per [Table - 1] and [Table - 2], there is reduction of total lymphocytes (T3), reduction of T4 and increase in T8 in both genralised and localised vitiligo. There was reduction of T4/T8 ratio. This ratio was more reduced in generalised than in localised type.
Regarding NK cells, there was reduction in localised and marked increase in generalised vitiligo.
[Table - 3] shows division of patients into 3 groups as per disease duration. In all the 3 groups there is reduction of T3 and T4. The reduction is more in group A. T8 is increased in all groups. The increase is most significant in group A. T4/T8 ratio is reduced in all groups. The reduction is most marked in group A.
[Table - 4] excludes localised cases and only generalised cases are considered. The 20 cases were again divided into 2 groups. Group A with disease duration less than 1 year and group B with disease duration more than 1 year. NK cells are increased in both the groups but this increase is more in group B patients.
Previous studies of T lymphocytes showed mixed results. Brown et al studied 24 patients with vitiligo. Of these 22 had reduced number of total T cells.
Ortonne and Alario studied T lymphocytes in a group of 38 patients. No abnormality was found by sheep RBC rosette. However, neither looked at T cell subsets or NK cells. Grimes et al studied T cell profiles in vitiligo. They found no statistically significant aberration in T cell profiles correlated with age, race, type of vitiligo, disease severity or associated disease. But as regards to disease duration, their patients had lower T cells in disease duration less than 1 year compared to those having disease duration of more than one year. Although the percentages were not significant, those having vitiligo for less than one year had lower T4/T8 ratio.
Soubiran et al found that T3 in circulation in vitiligo was not different from controls. However, the percentages of T4 was increased in vitiligo. Consequently, T4/T8 was increased in vitiligo despite a slight increase in T8 cells. This conformed to the picture of other autoimmune diseases.
Halder et al reported that there were abnormalities of T3, T4 T8 and NK cells in vitiligo. Specifically, total T and T4 cells were decreased in patients compared to normal, NK cells were increased and there was slight increase in T8 cells. They reported that there were trends in more qualitative aberration in total T, T4, T8 and NK cells in patients who had vitiligo for the shortest period. Regarding NK cells, patients with vitiligo had a greater number of Killer cells in comparison with control.
Our results are in agreement with Grimes et al and Halder et al in respect to disease duration. But in addition, as per clinical pattern we got significant finding previously not reported in any literature [Table - 1] and [Table - 2]. This was in contrast to the study of Grimes et al.
In both generalised and localised vitiligo there is a change in the number of T3, T4, T8 and T4/T8 ratio ie, low T3, T4 and T4/T8 ratio with increase in T8. This change is more marked in generalised variants. Although this finding does not conform to that of autoimmune diseases, this aberration may be of importance, although the significance of this aberration is unknown. It may be that T4 cells may migrate to vitiliginous skin and cause destruction of pigment cells, or T8 cells may be involved in Antibody Dependent Cell Cytotoxicity (ADCC) or directly cause destruction of melanocytes.
NK cells are maximally increased in generalised vitiligo and are low in the localised type. This can be due to the fact that a larger quantum of melanocyte destruction may require recruitment of another Killer cell in the from of NK cell is addition to T8 cells.
Regarding duration of disease, the aberration of T cell subsets (ie, low T3, low T4, increased T8, low T4/T8 ratio) is greatest when disease duration is shortest (ie, an inverse relationship). This signifies that this aberration is required for the initiation and development of the disease process. NK cells are more increased in the early part of the disease. So NK cells may take part not only in initiation but also in maintenance of the pathologic process.
Last of all, it should be mentioned that ours was a very small study involving only 30 patients. Due to limitation of time we did not do follow up studies. It would be of great value to study the cell subset change and NK cells in patients undergoing treatment.
| References|| |
|1.||Brown AC, Olkowski ZL, McLaren JR. The study of lymphocytes of the peripheral blood in patients with alopecia areata. Arch Dermatol 1977;133:633. |
|2.||Ortonne JP, Alario A. T and B lymphocytes in vitiligo. Arch Dermatol Res 1978;261:147-51. [PUBMED] |
|3.||Grimes PE, Ghoneum M, Stockton T, et al. T cell profile in vitiligo. J Am Acad Dermatol 1986;14:196-201. [PUBMED] |
|4.||Soubiran P, Bonzaken S, Bellet C, et al. Vitiligo: peripheral T subsets imbalance as defined by monoclonal antibodies. Br J Dermatol 1985; 113 (suppl 28): 124-7. |
|5.||Halder RM, Walter CS, Johnson BA, et al. Aberration in T lymphocytes and Natural Killer cell in vitiligo: a flow cytometric study. J Am Acad Dermatol 1986;14:733-7. |
[Table - 1], [Table - 2], [Table - 3], [Table - 4]