1035 FACTORS INFLUENCING DEVELOPMENT OF GROUP A STREPTOCOCCAL TYPE-SPECIFIC ANTIBODY

Abstract

Because factors influencing the immune response to streptococcal M protein following upper respiratory tract (URT) and skin infections are poorly understood, we evaluated epidemiologic data from 4 groups of patients (408 serially collected sera from 119 children; m age = 6.5 yrs.) followed carefully for 2 yrs. The date and site of first acquisition of 4 serotypes (6,31,49,52), and the type-specific serum bactericidal activity (SBA) from pre-and post-acquisition sera were determined. The effects of patient age, serotype, site of isolation and number of culture-positive visits for each M type on the development of SBA were studied. M-6 was isolated from only the URT; while M-31, 49, and 52 were isolated from both skin and URT. Significant SBA developed in 27 of 41 (66%) patients with M-6; 22 of 41 (54%) with M-31; 13 of 31 (42%) with M-49; and 4 of 6 (67%) with M-52. The magnitude of the SBA response was generally greater for those with M-6. Of those with M-31 or M-49, no difference in SBA was noted between those with recovery only from the URT and those with recovery from both the URT and skin lesions. The development of SBA was related to number of isolations, although different for those acquiring each type. The increase in SBA was age-related in those with M-6, but not in those with M-31 or M-49. These data define several complex variables which may influence development of SBA following group A streptococcal infections.