Antipneumococcal Protein Antibodies

The important role of type-specific anticapsular antibodies in host defense against pneumococcal infections is well established (1). The early successes of inducing type-specific protective antibodies (2) gave rise to numerous studies dealing with anticapsular antibodies and the development o f pneumococcal capsular polysaccharide vaccines (1). It has been suggested that antibodies to the pneumococcal cell wall are not opsonic and fail to protect mice from infection (3-5). However, there have been occasional reports o f protective antibody specific for noncapsular pneumococcal antigen(s) (6-9). More recently, it has been demonstra ted that monoclonal antibodies and C-reactive protein directed against phosphocholine (PC), 1 a cell wall determinant of pneumococcal C-carbohydrate (10), can protect mice from fatal infections with several types of Streptococcus pneumoniae (1 1 15). In the present study we have used monoclonal antibody techniques in an effort to characterize other cell wall determinants that may elicit protective antibody. xid mice, which respond poorly to carbohydrates (16, 17), were injected with an unencapsulated pneumococcus R36A in an effort to optimize the product ion of hybridoma antiprotein antibodies. Two hybridomas were produced which make antibodies that recognized protease-sensitive pneumococcal antigens and protected mice f rom infection with an encapsulated strain of S. pneumoniae.