XSS issue

Why is this label open to XSS and what should I add to fix the issue.

lbl_applicantName.Text = Helper.ConvertStringToTitleCase(applicantName);

public static string ConvertStringToTitleCase(string value)
        {
            //Create CultureInfo and TextInfo classes to use ToTitleCase method
            CultureInfo cultureInfo = Thread.CurrentThread.CurrentCulture;
            TextInfo textInfo = cultureInfo.TextInfo;
            if (value != null)
            {
                return textInfo.ToTitleCase(value.ToLower());
            }
            else
            {
                return "";
            }
        }