| Abstract: | Groups of newborn rats were transthoracically inoculated with 1 X 10(6) type III group B streptococci/g body wt, either alone or in combination with 1.5 microgram/g body wt of type-specific antibody derived from hybridoma cell lines. Ninety-four percent of the animals who received bacteria alone died. In contrast, none of those treated with antibody died (P less than 0.005). Kinetic studies suggested that antibody may have offered protection, In part, by facilitating the neutrophil response. Animals who received only bacteria exhibited a marked neutropenia (20 +/- 18/mm3, mean +/- S.E.M.) whereas infected animals treated with antibody did not (3800 +/- 30/mm3, P less than 0.001). Furthermore, within 2 h of inoculation, antibody-treated animals mobilized and stored neutrophils, whereas significant neutrophil mobilization did not occur in the animals which received bacteria alone until 6 h. In the animals receiving bacteria alone, exhaustion of the neutrophil supply quickly occurred (remaining storage neutrophils at 6 h, 0.2 +/- 0.1 X 10(6) cells). In contrast, animals, which received antibody, maintained an adequate supply of stored neutrophils (7.0 +/- 0.4 X 10(6) P less than 0.001). The migration of neutrophils to the site of inoculation was measured by assaying the lungs' content of myeloperoxidase, a marker enzyme for granulocytes. The right and left lungs of animals not receiving antibody accumulated the same quantity of neutrophils, with peak pulmonary neutrophil accumulation occurring 6 h after the infection. In antibody recipients, however, the inoculated lung accumulated significantly more neutrophils than the opposite lung and peak pulmonary neutrophil accumulation occurred at 2 rather than 6 h. |
