Oral administration of a bacterial immunomodulator enhances murine intestinal lamina propria and Peyer's patch lymphocyte traffic to the lung: possible implications for infectious disease prophylaxis and therapy

LW50020, a bacterial immunomodulator, is a preparation consistingof seven bacteria, commonly causing respiratory disease. Whengiven orally, LW50020 has been shown to enhance the host defenseof the respiratory tract. Intestinal lamina propria lymphocytes(LPL), Peyer's patch lymphocytes (PPL), and splenocytes fromBALB/c mice gavaged either with LW50020 or carrier alone wereisolated, labeled with either H33342, a supravital nuclear fluorochrome,or ⁵¹Cr, and injected i.v. into untreated, age-matched BALB/cmice. Two hours later, spleen, liver, lung, kidneys, Peyer'spatch, and mesenteric lymph nodes of the recipients were harvestedand screened for the presence of labeled cells. LPL from micegavaged with carrier only (controls) migrated preferentiallyto the lung, PPL equally well to the lung, and the spleen andsplenocytes were found mostly in the spleen. LPL and PPL fromLW50020-treated mice were found in significantly larger numbersin the lungs of recipients than LPL and PPL from control animals.Both labeling techniques gave roughly the same results. Sixty-fiveper cent of LPL in the lung were Thy-1.2⁺ and 20% B cells. Thesefindings should contribute to the understanding of parametersnecessary for the assessment of the mode of action and efficacyof immunomodulation and vaccination via the mucosa-associatedlymphoid tissue.