A Study of Tolerability and Safety of Two New Doses of Grass MATA MPL

Inclusion Criteria: * Patients must have a positive skin prick test for grass pollen allergen. * Positive skin prick test to positive histamine control * Negative skin prick test to negative control * Specific IgE for grass pollen as documented by radioallergosorbent or equivalent test with class ≥ 2 * History of at least 2 seasons of moderate to severe seasonal rhinoconjunctivitis due to an IgE - mediated allergy to pollen from grass * Males or non-pregnant, non-lactating females who are: * Post-menopausal (defined as at least 12 months natural spontaneous amenorrhea or at least 6 weeks following surgical menopause, i.e. bilateral oophorectomy) * Naturally or surgically sterile (hysterectomy; bilateral oophorectomy; bilateral tubal ligation with surgery at least 6 weeks prior to study initiation) * Of childbearing potential - with negative urinary and serological pregnancy test and use at least one of the following contraception methods: * Stable hormonal contraceptive for ≥ 90 days prior to Visit 1 and at least 7 days after the final injection. If \< 90 days prior to the study, additional use of a double barrier method until 90 days reached is required. * Placement of an intrauterine device (IUD) or intrauterine system * Use of barrier methods of contraception (e.g., condom or occlusive cap) with spermicidal foam/gel/film/cream /suppository * Use of double barrier methods of contraception (e.g., male condom with diaphragm, male condom with cervical cap) * Pa…