Thl and Th2 cytokine profiles in uncomplicated measles infection among a group of Ghanain children.

ABSTRACT

Measles remains a major severe infectious disease causing deaths of many children in

most countries including Ghana. The disorder is associated with prolonged

immunosuppression resulting in complications and mortality in children. Although

attempts have been made to identify the specific immune functions altered during

measles, the exact immune changes have not been fully characterized. The pro and

anti-inflammatory response balances (Thl/Th2) are important in determining the

pathogenesis and course of viral infections in general.

CD4 mediated T cell responses to infectious agents may be dominated by type 1 or

type 2 cells. Cell types are identified by the arrays of cytokine produced by each and

have been clearly defined for mouse T cell clones. Similar distinctive patterns of

cytokine production have been described for human T cell clones. Type 1 CD4 T cells

secrete IL-2, IFN-y and preferentially induce macrophage activation and delayed type

hypersensitivity. Type 2 CD4 T cells produce IL-4, IL-5, IL-6 and IL-10, provide help

for B cell responses and decrease macrophage activation. These subtypes of CD4 T

cells are cross-regulatory. IFN-y inhibits proliferation of type 2 CD4 cells whereas IL-

4 and EL-10 inhibit cytokine production by type 1 CD4 cells either directly or through

their effects on macrophages.

In this study, the profiles of Thl (IFN-y, TNF-a) and Th2 (IL-4, IL-10, TGF|3)

cytokine expression in vivo during uncomplicated measles among a group of

Ghanaian children aged 12 years and below, mean age 6.2 ± 3.5 years were

determined on days 0 (acute phase), 14 and 60 (convalescence stages). Results

obtained were compared with age and sex-matched healthy controls. The results

clearly showed high plasma levels of interleukin-4 (IL-4) a Th2 and an antiinflammatory

cytokine, early in the acute phase (day 0) of the disease, which declined

by day 14, and day 60 post infection. Accompanying IL-4 up-regulation,

Transforming growth factor (3-1 (TGF-(3l) another anti-inflammatory cytokine also

increased significantly and remained elevated in plasma samples of all patients

throughout the study period (day 0, 14 and 60).

The data however showed low levels of tumour necrosis factor alpha (TNF-a), a proinflammatory

cytokine in the plasma samples of the patients at the acute and

convalescent phases of the illness, and there was no significant difference observed

between measles patients and healthy controls.

Plasma levels of interleukin 12 (IL-12) and interleukin-2 (IL-2) were low in the study

subjects on days 0, 14 and 60. IL-12 is critical for the orchestration of cellular

immunity for the resolution of measles infection and in this study; IL-12 suppression

was prolonged for 2 months after recovery from measles.

Plasma levels of the Thl cytokine, interferon gamma (INF-y) increased significantly

(p